Misc tweaks

Allow nickname->species with span
add ConstantExpected annotations
Correct Gen8b ability set calling CommonEdits instead of direct setter
Slightly better perf on gen5/gen8+ location fetch
Misc pkm ctor fixes for b2w2 trade & wc3 eggs
wurmple evo now has an enum to be more explicit
no recursion for gen5 generator
fix showdown line length check allowing 86 instead of 80

PKHeX.Core/Editing/CommonEdits.cs

@@ -51,7 +51,7 @@ public static class CommonEdits
     /// Sets the <see cref="PKM.Ability"/> value by sanity checking the provided <see cref="PKM.Ability"/> against the possible pool of abilities.
     /// </summary>
     /// <param name="pk">Pokémon to modify.</param>
-    /// <param name="abil">Desired <see cref="PKM.Ability"/> to set.</param>
+    /// <param name="abil">Desired <see cref="Ability"/> value to set.</param>
     public static void SetAbility(this PKM pk, int abil)
     {
         if (abil < 0)

PKHeX.Core/Editing/Showdown/ShowdownSet.cs

@@ -145,7 +145,8 @@ public sealed class ShowdownSet : IBattleTemplate
     // We will handle this 1-2 letter edge case only if the line is the first line of the set, in the rare chance we are importing for a non-English language?
     private const int MinLength = 3;
     private const int MaxLength = 80;
-    private static bool IsLengthOutOfRange(ReadOnlySpan<char> trim) => (uint)(trim.Length - MinLength) > MaxLength + MinLength;
+    private static bool IsLengthOutOfRange(ReadOnlySpan<char> trim) => IsLengthOutOfRange(trim.Length);
+    private static bool IsLengthOutOfRange(int length) => (uint)(length - MinLength) > MaxLength - MinLength;
 
     private void ParseLines(SpanLineEnumerator lines)
     {

PKHeX.Core/Editing/WurmpleUtil.cs

@@ -10,23 +10,22 @@ public static class WurmpleUtil
     /// </summary>
     /// <param name="encryptionConstant">Encryption Constant</param>
     /// <returns>Wurmple Evolution Value</returns>
-    public static uint GetWurmpleEvoVal(uint encryptionConstant)
+    public static WurmpleEvolution GetWurmpleEvoVal(uint encryptionConstant)
     {
         var evoVal = encryptionConstant >> 16;
-        return evoVal % 10 / 5;
+        return (WurmpleEvolution)(evoVal % 10 / 5);
     }
 
     /// <summary>
     /// Gets the evo chain of Wurmple
     /// </summary>
-    /// <param name="species">Current species</param>
-    /// <returns>-1 if not a Wurmple Evo, 0 if Silcoon chain, 1 if Cascoon chain</returns>
-    public static int GetWurmpleEvoGroup(ushort species)
+    /// <param name="species">Current species, must be evolved from Wurmple.</param>
+    public static WurmpleEvolution GetWurmpleEvoGroup(ushort species)
     {
         int wIndex = species - (int)Species.Silcoon;
         if ((wIndex & 3) != wIndex) // Wurmple evo, [0,3]
-            return -1;
-        return wIndex >> 1; // Silcoon, Cascoon
+            return WurmpleEvolution.None;
+        return (WurmpleEvolution)(wIndex >> 1); // Silcoon, Cascoon
     }
 
     /// <summary>
@@ -35,7 +34,7 @@ public static class WurmpleUtil
     /// <param name="evoVal">Wurmple Evolution Value</param>
     /// <remarks>0 = Silcoon, 1 = Cascoon</remarks>
     /// <returns>Encryption Constant</returns>
-    public static uint GetWurmpleEncryptionConstant(int evoVal)
+    public static uint GetWurmpleEncryptionConstant(WurmpleEvolution evoVal)
     {
         uint result;
         var rnd = Util.Rand;
@@ -51,8 +50,23 @@ public static class WurmpleUtil
     /// <returns>True if valid, false if invalid</returns>
     public static bool IsWurmpleEvoValid(PKM pk)
     {
-        uint evoVal = GetWurmpleEvoVal(pk.EncryptionConstant);
-        int wIndex = GetWurmpleEvoGroup(pk.Species);
+        var evoVal = GetWurmpleEvoVal(pk.EncryptionConstant);
+        var wIndex = GetWurmpleEvoGroup(pk.Species);
         return evoVal == wIndex;
     }
 }
+
+/// <summary>
+/// Indicates the evolution of Wurmple
+/// </summary>
+public enum WurmpleEvolution
+{
+    /// <summary> Invalid value </summary>
+    None = -1,
+
+    /// <summary> Evolves into Silcoon/Beautifly </summary>
+    Silcoon = 0,
+
+    /// <summary> Evolves into Cascoon/Dustox </summary>
+    Cascoon = 1,
+}

PKHeX.Core/Game/GameStrings/GameLanguage.cs

@@ -62,54 +62,3 @@ public static class GameLanguage
         return data;
     }
 }
-
-/// <summary>
-/// Program Languages supported; mirrors <see cref="GameLanguage.LanguageCodes"/>.
-/// </summary>
-public enum ProgramLanguage
-{
-    /// <summary>
-    /// Japanese
-    /// </summary>
-    日本語,
-
-    /// <summary>
-    /// English
-    /// </summary>
-    English,
-
-    /// <summary>
-    /// French
-    /// </summary>
-    Français,
-
-    /// <summary>
-    /// Italian
-    /// </summary>
-    Italiano,
-
-    /// <summary>
-    /// German
-    /// </summary>
-    Deutsch,
-
-    /// <summary>
-    /// Spanish
-    /// </summary>
-    Español,
-
-    /// <summary>
-    /// Korean
-    /// </summary>
-    한국어,
-
-    /// <summary>
-    /// Simplified Chinese
-    /// </summary>
-    简体中文,
-
-    /// <summary>
-    /// Traditional Chinese
-    /// </summary>
-    繁體中文,
-}

PKHeX.Core/Game/GameStrings/MetDataSource.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using static PKHeX.Core.GameVersion;
 using static PKHeX.Core.Locations;
 
@@ -101,12 +102,15 @@ public sealed class MetDataSource
     private IReadOnlyList<ComboItem> CreateGen5Transfer()
     {
         // PokéTransfer to front
-        var met = MetGen5.ToArray();
-        var index = Array.FindIndex(met, static z => z.Value == Locations.Transfer4);
-        var xfr = met[index];
-        Array.Copy(met, 0, met, 1, index);
-        met[0] = xfr;
-        return met;
+        var index = MetGen5.FindIndex(static z => z.Value == Locations.Transfer4);
+        var xfr = MetGen5[index];
+        var result = new ComboItem[MetGen5.Count];
+        result[0] = xfr;
+        var dest = result.AsSpan(1);
+        var span = CollectionsMarshal.AsSpan(MetGen5);
+        span[..index].CopyTo(dest);
+        span[(index + 1)..].CopyTo(dest[index..]);
+        return result;
     }
 
     private static List<ComboItem> CreateGen6(GameStrings s)
@@ -230,10 +234,15 @@ public sealed class MetDataSource
         // Insert the BDSP none location if the format requires it.
         if (context is EntityContext.Gen8b && !BDSP.Contains(version))
         {
-            var list = new List<ComboItem>(result.Count + 1);
-            list.AddRange(result);
-            list.Insert(1, new ComboItem($"{list[0].Text} (BD/SP)", Locations.Default8bNone));
-            result = list;
+            var bdsp = new ComboItem[result.Count + 1];
+            var none = bdsp[0] = result[0];
+            bdsp[1] = new ComboItem($"{none.Text} (BD/SP)", Locations.Default8bNone);
+            var dest = bdsp.AsSpan(2);
+            if (result is ComboItem[] arr)
+                arr.AsSpan(1).CopyTo(dest);
+            else if (result is List<ComboItem> list)
+                CollectionsMarshal.AsSpan(list)[1..].CopyTo(dest);
+            return bdsp;
         }
 
         return result;

PKHeX.Core/Game/GameStrings/ProgramLanguage.cs

@@ -0,0 +1,52 @@
+namespace PKHeX.Core;
+
+/// <summary>
+/// Program Languages supported; mirrors <see cref="GameLanguage.LanguageCodes"/>.
+/// </summary>
+public enum ProgramLanguage
+{
+    /// <summary>
+    /// Japanese
+    /// </summary>
+    日本語,
+
+    /// <summary>
+    /// English
+    /// </summary>
+    English,
+
+    /// <summary>
+    /// French
+    /// </summary>
+    Français,
+
+    /// <summary>
+    /// Italian
+    /// </summary>
+    Italiano,
+
+    /// <summary>
+    /// German
+    /// </summary>
+    Deutsch,
+
+    /// <summary>
+    /// Spanish
+    /// </summary>
+    Español,
+
+    /// <summary>
+    /// Korean
+    /// </summary>
+    한국어,
+
+    /// <summary>
+    /// Simplified Chinese
+    /// </summary>
+    简体中文,
+
+    /// <summary>
+    /// Traditional Chinese
+    /// </summary>
+    繁體中文,
+}

PKHeX.Core/Legality/Encounters/Data/EncounterEvent.cs

@@ -73,9 +73,6 @@ public static class EncounterEvent
     public static WC9[] EGDB_G9 { get; private set; } = Array.Empty<WC9>();
     #endregion
 
-    /// <summary>Indicates if the databases are initialized.</summary>
-    public static bool Initialized => MGDB_G3.Length != 0;
-
     private static PCD[] GetPCDDB(ReadOnlySpan<byte> bin) => Get(bin, PCD.Size, static d => new PCD(d));
     private static PGF[] GetPGFDB(ReadOnlySpan<byte> bin) => Get(bin, PGF.Size, static d => new PGF(d));
 
@@ -178,6 +175,7 @@ public static class EncounterEvent
     {
         var regular = new IReadOnlyList<MysteryGift>[]
         {
+            MGDB_G3,
             MGDB_G4,       EGDB_G4,
             MGDB_G5,       EGDB_G5,
             MGDB_G6,       EGDB_G6,
@@ -188,8 +186,7 @@ public static class EncounterEvent
             MGDB_G8B,      EGDB_G8B,
             MGDB_G9,       EGDB_G9,
         }.SelectMany(z => z);
-        regular = regular.Where(mg => mg is { IsItem: false, IsEntity: true, Species: > 0 });
-        var result = MGDB_G3.Concat(regular);
+        var result = regular.Where(mg => mg is { IsItem: false, IsEntity: true, Species: not 0 });
         if (sorted)
             result = result.OrderBy(mg => mg.Species);
         return result;

PKHeX.Core/Legality/Encounters/Data/Gen3/Encounters3Colo.cs

@@ -11,7 +11,7 @@ internal static class Encounters3Colo
         new(197, 26) { Moves = new(044, 269, 290, 289) }, // Umbreon (Bite)
     };
 
-    internal static readonly string[] TrainerNameDuking = { string.Empty, "ギンザル", "DUKING", "DOKING", "RODRIGO", "GRAND", string.Empty, "GERMÁN", };
+    internal static readonly string[] TrainerNameDuking = { string.Empty, "ギンザル", "DUKING", "DOKING", "RODRIGO", "GRAND", string.Empty, "GERMÁN" };
 
     internal static readonly EncounterGift3Colo[] Gifts =
     {

PKHeX.Core/Legality/Encounters/Data/Gen8/Encounters8a.cs

@@ -15,12 +15,12 @@ internal static class Encounters8a
     internal static readonly EncounterStatic8a[] StaticLA =
     {
         // Gifts
-        new(722,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed, }, // Rowlet
-        new(155,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed, }, // Cyndaquil
-        new(501,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed, }, // Oshawott
-        new(037,001,40,M,M) { Location = 088,                      FixedBall = Ball.LAPoke,   Method = Fixed, }, // Vulpix-1
-        new(483,000,65,M,M) { Location = 109, FlawlessIVCount = 3, FixedBall = Ball.LAOrigin, Method = Fixed, }, // Dialga
-        new(484,000,65,M,M) { Location = 109, FlawlessIVCount = 3, FixedBall = Ball.LAOrigin, Method = Fixed, }, // Palkia
+        new(722,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed }, // Rowlet
+        new(155,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed }, // Cyndaquil
+        new(501,000,05,M,M) { Location = 006,                      FixedBall = Ball.LAPoke,   Method = Fixed }, // Oshawott
+        new(037,001,40,M,M) { Location = 088,                      FixedBall = Ball.LAPoke,   Method = Fixed }, // Vulpix-1
+        new(483,000,65,M,M) { Location = 109, FlawlessIVCount = 3, FixedBall = Ball.LAOrigin, Method = Fixed }, // Dialga
+        new(484,000,65,M,M) { Location = 109, FlawlessIVCount = 3, FixedBall = Ball.LAOrigin, Method = Fixed }, // Palkia
         new(493,000,75,M,M) { Location = 109, FlawlessIVCount = 3, FixedBall = Ball.LAPoke,   Method = Fixed, FatefulEncounter = true }, // Arceus
 
         // Static Encounters - Scripted Table Slots

PKHeX.Core/Legality/Encounters/Data/Live/EncountersGO.cs

@@ -1,16 +1,16 @@
-namespace PKHeX.Core;
+namespace PKHeX.Core;
 
 /// <summary>
 /// Encounter data from <see cref="GameVersion.GO"/>, which has multiple generations of origin.
 /// </summary>
 #if !DEBUG
-    internal static class EncountersGO
-    {
-        internal const int MAX_LEVEL = 50;
+internal static class EncountersGO
+{
+    internal const int MAX_LEVEL = 50;
 
-        internal static readonly EncounterArea7g[] SlotsGO_GG = EncounterArea7g.GetArea(EncounterUtil.Get("go_lgpe", "go"));
-        internal static readonly EncounterArea8g[] SlotsGO = EncounterArea8g.GetArea(EncounterUtil.Get("go_home", "go"));
-    }
+    internal static readonly EncounterArea7g[] SlotsGO_GG = EncounterArea7g.GetArea(EncounterUtil.Get("go_lgpe", "go"));
+    internal static readonly EncounterArea8g[] SlotsGO = EncounterArea8g.GetArea(EncounterUtil.Get("go_home", "go"));
+}
 #else
 public static class EncountersGO
 {

PKHeX.Core/Legality/Encounters/Generator/Search/EncounterEnumerator5.cs

@@ -95,10 +95,13 @@ public record struct EncounterEnumerator5(PKM Entity, EvoCriteria[] Chain, GameV
                 State = YieldState.BredSplit;
                 return SetCurrent(egg);
             case YieldState.BredSplit:
-                State = Entity.Egg_Location == Locations.Daycare5 ? YieldState.End : YieldState.StartCaptures;
-                if (!EncounterGenerator5.TryGetSplit((EncounterEgg)Current.Encounter, Chain, out egg))
-                    return MoveNext();
-                return SetCurrent(egg);
+                bool daycare = Entity.Egg_Location == Locations.Daycare5;
+                State = daycare ? YieldState.End : YieldState.StartCaptures;
+                if (EncounterGenerator5.TryGetSplit((EncounterEgg)Current.Encounter, Chain, out egg))
+                    return SetCurrent(egg);
+                if (daycare)
+                    break; // no other encounters
+                goto case YieldState.StartCaptures;
 
             case YieldState.TradeStart:
                 if (Version == GameVersion.W)

PKHeX.Core/Legality/Encounters/Templates/Gen5/EncounterTrade5B2W2.cs

@@ -102,9 +102,10 @@ public sealed record EncounterTrade5B2W2 : IEncounterable, IEncounterMatch, IFix
     {
         if (pk.IsShiny)
             pk.PID ^= 0x1000_0000;
-        pk.Nature = (int)criteria.GetNature(Nature.Random);
-        pk.Gender = criteria.GetGender(-1, pi);
-        pk.RefreshAbility(criteria.GetAbilityFromNumber(Ability));
+        var nature = (int)criteria.GetNature(Nature);
+        var gender = criteria.GetGender(Gender, pi);
+        var ability = criteria.GetAbilityFromNumber(Ability);
+        PIDGenerator.SetRandomWildPID5(pk, nature, ability, gender);
         criteria.SetRandomIVs(pk, IVs);
     }
 

PKHeX.Core/Legality/Encounters/Templates/Gen9/EncounterFixed9.cs

@@ -20,7 +20,7 @@ public sealed record EncounterFixed9
     public Ball FixedBall => Ball.None;
     public bool IsShiny => false;
     public int EggLocation => 0;
-    public AbilityPermission Ability => AbilityPermission.Any12;
+    public AbilityPermission Ability => Any12;
 
     public required ushort Species { get; init; }
     public required byte Form { get; init; }

PKHeX.Core/Legality/RNG/Methods/Roaming8bRNG.cs

@@ -92,7 +92,7 @@ public static class Roaming8bRNG
         pk.IV_SPE = ivs[5];
 
         // Ability
-        pk.SetAbilityIndex((int)xoro.NextUInt(2));
+        pk.RefreshAbility((int)xoro.NextUInt(2));
 
         // Remainder
         var scale = (IScaledSize)pk;

PKHeX.Core/Legality/RNG/Methods/Wild8bRNG.cs

@@ -103,7 +103,7 @@ public static class Wild8bRNG
             AbilityPermission.Any12H => (int)xors.NextUInt(3),
             _ => (int)ability >> 1,
         };
-        pk.SetAbilityIndex(n);
+        pk.RefreshAbility(n);
 
         // Gender (skip this if gender is fixed)
         var genderRatio = PersonalTable.BDSP.GetFormEntry(pk.Species, pk.Form).Gender;

PKHeX.Core/Legality/Verifiers/NicknameVerifier.cs

@@ -22,7 +22,7 @@ public sealed class NicknameVerifier : Verifier
             data.AddLine(GetInvalid(LNickLengthShort));
             return;
         }
-        if (pk.Species > SpeciesName.SpeciesLang[0].Count)
+        if (pk.Species > SpeciesName.MaxSpeciesID)
         {
             data.AddLine(Get(LNickLengthShort, Severity.Invalid));
             return;
@@ -143,7 +143,7 @@ public sealed class NicknameVerifier : Verifier
             data.AddLine(GetInvalid(LNickMatchLanguageFlag));
     }
 
-    private bool VerifyUnNicknamedEncounter(LegalityAnalysis data, PKM pk, string nickname)
+    private bool VerifyUnNicknamedEncounter(LegalityAnalysis data, PKM pk, ReadOnlySpan<char> nickname)
     {
         if (pk.IsNicknamed)
         {
@@ -157,11 +157,11 @@ public sealed class NicknameVerifier : Verifier
                     return true;
                 }
             }
-            for (int i = 0; i < SpeciesName.SpeciesDict.Count; i++)
+            foreach (var language in Language.GetAvailableGameLanguages(pk.Format))
             {
-                if (!SpeciesName.SpeciesDict[i].TryGetValue(nickname, out var species))
+                if (!SpeciesName.TryGetSpecies(nickname, language, out var species))
                     continue;
-                var msg = species == pk.Species && i != pk.Language ? LNickMatchNoOthersFail : LNickMatchLanguageFlag;
+                var msg = species == pk.Species && language != pk.Language ? LNickMatchNoOthersFail : LNickMatchLanguageFlag;
                 data.AddLine(Get(msg, ParseSettings.NicknamedAnotherSpecies));
                 return true;
             }

PKHeX.Core/Legality/Verifiers/PIDVerifier.cs

@@ -84,8 +84,8 @@ public sealed class PIDVerifier : Verifier
         if (pk.Species == (int)Species.Wurmple)
         {
             // Indicate what it will evolve into
-            uint evoVal = WurmpleUtil.GetWurmpleEvoVal(pk.EncryptionConstant);
-            var evolvesTo = evoVal == 0 ? (int)Species.Beautifly : (int)Species.Dustox;
+            var evoVal = WurmpleUtil.GetWurmpleEvoVal(pk.EncryptionConstant);
+            var evolvesTo = evoVal == WurmpleEvolution.Silcoon ? (int)Species.Beautifly : (int)Species.Dustox;
             var species = ParseSettings.SpeciesStrings[evolvesTo];
             var msg = string.Format(L_XWurmpleEvo_0, species);
             data.AddLine(GetValid(msg, CheckIdentifier.EC));

PKHeX.Core/MysteryGifts/WC3.cs

@@ -127,7 +127,11 @@ public sealed class WC3 : MysteryGift, IRibbonSetEvent3, ILangNicknamedTemplate,
             pk.Language = (int)GetSafeLanguage((LanguageID)tr.Language);
             pk.OT_Name = !string.IsNullOrWhiteSpace(OT_Name) ? OT_Name : tr.OT;
             if (IsEgg)
+            {
                 pk.IsEgg = true; // lang should be set to japanese already
+                if (pk.OT_Trash[0] == 0xFF)
+                    pk.OT_Name = "ゲーフリ";
+            }
         }
         pk.Nickname = Nickname ?? SpeciesName.GetSpeciesNameGeneration(Species, pk.Language, 3); // will be set to Egg nickname if appropriate by PK3 setter
 
@@ -200,6 +204,7 @@ public sealed class WC3 : MysteryGift, IRibbonSetEvent3, ILangNicknamedTemplate,
         var seed = Util.Rand32();
         seed = TID16 == 06930 ? MystryMew.GetSeed(seed, Method) : GetSaneSeed(seed);
         PIDGenerator.SetValuesFromSeed(pk, Method, seed);
+        pk.RefreshAbility((int)(pk.EncryptionConstant & 1));
     }
 
     private uint GetSaneSeed(uint seed) => Method switch

PKHeX.Core/PKM/HOME/HomeOptional1.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
@@ -19,7 +20,7 @@ public abstract class HomeOptional1
     protected HomeOptional1(ushort size) => Buffer = new byte[size];
     protected HomeOptional1(Memory<byte> buffer) => Buffer = buffer;
 
-    protected void EnsureSize(int size)
+    protected void EnsureSize([ConstantExpected] int size)
     {
         if (Buffer.Length != size)
             throw new ArgumentOutOfRangeException(nameof(size), size, $"Expected size {Buffer.Length} but received {size}.");

PKHeX.Core/PKM/PKM.cs

@@ -27,7 +27,7 @@ public abstract class PKM : ISpeciesForm, ITrainerID32, IGeneration, IShiny, ILa
     public readonly byte[] Data; // Raw Storage
 
     protected PKM(byte[] data) => Data = data;
-    protected PKM(int size) => Data = new byte[size];
+    protected PKM([ConstantExpected] int size) => Data = new byte[size];
 
     public virtual byte[] EncryptedPartyData => Encrypt().AsSpan(0, SIZE_PARTY).ToArray();
     public virtual byte[] EncryptedBoxData => Encrypt().AsSpan(0, SIZE_STORED).ToArray();
@@ -939,25 +939,6 @@ public abstract class PKM : ISpeciesForm, ITrainerID32, IGeneration, IShiny, ILa
         SetIVs(ivs);
     }
 
-    /// <summary>
-    /// Randomizes the IVs within game constraints.
-    /// </summary>
-    /// <param name="template">IV template to generate from</param>
-    /// <param name="minFlawless">Count of flawless IVs to set. If none provided, a count will be detected.</param>
-    /// <returns>Randomized IVs if desired.</returns>
-    public void SetRandomIVsTemplate(IndividualValueSet template, int minFlawless = 0)
-    {
-        Span<int> ivs = stackalloc int[6];
-        var rnd = Util.Rand;
-        do
-        {
-            for (int i = 0; i < 6; i++)
-                ivs[i] = template[i] < 0 ? rnd.Next(MaxIV + 1) : template[i];
-        } while (ivs.Count(MaxIV) < minFlawless);
-
-        SetIVs(ivs);
-    }
-
     /// <summary>
     /// Applies all shared properties from the current <see cref="PKM"/> to the <see cref="result"/> <see cref="PKM"/>.
     /// </summary>

PKHeX.Core/PKM/Shared/G3PKM.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace PKHeX.Core;
 
@@ -8,7 +9,7 @@ namespace PKHeX.Core;
 public abstract class G3PKM : PKM, IRibbonSetEvent3, IRibbonSetCommon3, IRibbonSetUnique3, IRibbonSetOnly3, IRibbonSetRibbons, IContestStats
 {
     protected G3PKM(byte[] data) : base(data) { }
-    protected G3PKM(int size) : base(size) { }
+    protected G3PKM([ConstantExpected] int size) : base(size) { }
 
     public abstract override PersonalInfo3 PersonalInfo { get; }
 

PKHeX.Core/PKM/Shared/G4PKM.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace PKHeX.Core;
 
@@ -7,7 +8,7 @@ public abstract class G4PKM : PKM,
     IRibbonSetEvent3, IRibbonSetEvent4, IRibbonSetUnique3, IRibbonSetUnique4, IRibbonSetCommon3, IRibbonSetCommon4, IRibbonSetRibbons, IContestStats, IGroundTile
 {
     protected G4PKM(byte[] data) : base(data) { }
-    protected G4PKM(int size) : base(size) { }
+    protected G4PKM([ConstantExpected] int size) : base(size) { }
 
     // Maximums
     public sealed override ushort MaxMoveID => Legal.MaxMoveID_4;

PKHeX.Core/PKM/Shared/G6PKM.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace PKHeX.Core;
 
@@ -8,7 +9,7 @@ public abstract class G6PKM : PKM, ISanityChecksum
     public override int SIZE_PARTY => PokeCrypto.SIZE_6PARTY;
     public override int SIZE_STORED => PokeCrypto.SIZE_6STORED;
     protected G6PKM(byte[] data) : base(data) { }
-    protected G6PKM(int size) : base(size) { }
+    protected G6PKM([ConstantExpected] int size) : base(size) { }
 
     // Trash Bytes
     public sealed override Span<byte> Nickname_Trash => Data.AsSpan(0x40, 26);

PKHeX.Core/PKM/Shared/GBPKM.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace PKHeX.Core;
 
@@ -19,7 +20,7 @@ public abstract class GBPKM : PKM
 
     public sealed override ReadOnlySpan<ushort> ExtraBytes => ReadOnlySpan<ushort>.Empty;
 
-    protected GBPKM(int size) : base(size) { }
+    protected GBPKM([ConstantExpected] int size) : base(size) { }
     protected GBPKM(byte[] data) : base(data) { }
 
     public sealed override byte[] EncryptedPartyData => Encrypt();

PKHeX.Core/PKM/Util/Language.cs

@@ -29,6 +29,11 @@ public static class Language
     private static ReadOnlySpan<byte> Languages_3  => Languages[..6]; // [..KOR)
     private const LanguageID SafeLanguage = English;
 
+    /// <summary>
+    /// Returns the available languages for the given generation.
+    /// </summary>
+    /// <param name="generation">Generation to check.</param>
+    /// <returns>Available languages for the given generation.</returns>
     public static ReadOnlySpan<byte> GetAvailableGameLanguages(int generation = PKX.Generation) => generation switch
     {
         1           => Languages_3, // No KOR
@@ -40,6 +45,13 @@ public static class Language
 
     private static bool HasLanguage(ReadOnlySpan<byte> permitted, byte language) => permitted.Contains(language);
 
+    /// <summary>
+    /// Returns the language that is safe to use for the given generation.
+    /// </summary>
+    /// <param name="generation">Generation to check.</param>
+    /// <param name="prefer">Preferred language.</param>
+    /// <param name="game">Game version to check.</param>
+    /// <returns>Language that is safe to use for the given generation.</returns>
     public static LanguageID GetSafeLanguage(int generation, LanguageID prefer, GameVersion game = GameVersion.Any) => generation switch
     {
         1 when game == GameVersion.BU => Japanese,
@@ -50,6 +62,11 @@ public static class Language
         _           => HasLanguage(Languages,    (byte)prefer) ? prefer : SafeLanguage,
     };
 
+    /// <summary>
+    /// Gets the 2-character language name for the given <see cref="LanguageID"/>.
+    /// </summary>
+    /// <param name="language">Language ID to get the 2-character name for.</param>
+    /// <returns>2-character language name.</returns>
     public static string GetLanguage2CharName(this LanguageID language) => language switch
     {
         Japanese => "ja",

PKHeX.Core/PKM/Util/SpeciesName.cs

@@ -13,7 +13,7 @@ public static class SpeciesName
     /// <summary>
     /// Species name lists indexed by the <see cref="LanguageID"/> value.
     /// </summary>
-    public static readonly IReadOnlyList<IReadOnlyList<string>> SpeciesLang = new[]
+    private static readonly IReadOnlyList<IReadOnlyList<string>> SpeciesLang = new[]
     {
         Util.GetSpeciesList("ja"), // 0 (unused, invalid)
         Util.GetSpeciesList("ja"), // 1
@@ -28,6 +28,11 @@ public static class SpeciesName
         Util.GetSpeciesList("zh2"), // 10 Traditional
     };
 
+    /// <summary>
+    /// Gets the maximum valid species ID stored in the <see cref="SpeciesLang"/> list.
+    /// </summary>
+    public static readonly ushort MaxSpeciesID = (ushort)(SpeciesLang[0].Count - 1);
+
     /// <summary>
     /// Egg name list indexed by the <see cref="LanguageID"/> value.
     /// </summary>
@@ -50,7 +55,25 @@ public static class SpeciesName
     /// <summary>
     /// <see cref="PKM.Nickname"/> to <see cref="Species"/> table for all <see cref="LanguageID"/> values.
     /// </summary>
-    public static readonly IReadOnlyList<Dictionary<string, int>> SpeciesDict = Util.GetMultiDictionary(SpeciesLang, 1);
+    private static readonly IReadOnlyList<Dictionary<int, ushort>> SpeciesDict = GetDictionary(SpeciesLang);
+
+    private static IReadOnlyList<Dictionary<int, ushort>> GetDictionary(IReadOnlyList<IReadOnlyList<string>> names)
+    {
+        var result = new Dictionary<int, ushort>[names.Count];
+        for (int i = 0; i < result.Length; i++)
+        {
+            var dict = new Dictionary<int, ushort>();
+            var speciesList = names[i];
+            for (ushort species = 1; species < speciesList.Count; species++)
+            {
+                var name = speciesList[species];
+                var hash = string.GetHashCode(name);
+                dict.Add(hash, species);
+            }
+            result[i] = dict;
+        }
+        return result;
+    }
 
     /// <summary>
     /// Gets a Pokémon's default name for the desired language ID.
@@ -270,19 +293,18 @@ public static class SpeciesName
     /// </summary>
     /// <param name="speciesName">Species Name</param>
     /// <param name="language">Language the name is from</param>
-    /// <returns>Species ID</returns>
-    /// <remarks>Only use this for modern era name -> ID fetching.</remarks>
-    public static int GetSpeciesID(string speciesName, int language = (int)LanguageID.English)
+    /// <param name="species">Species ID</param>
+    /// <returns>True if the species was found, False if not</returns>
+    public static bool TryGetSpecies(ReadOnlySpan<char> speciesName, int language, out ushort species)
     {
-        if (SpeciesDict[language].TryGetValue(speciesName, out var value))
-            return value;
-
-        // stupid ’, ignore language if we match these.
-        return speciesName switch
-        {
-            "Farfetch'd" => (int)Species.Farfetchd,
-            "Sirfetch'd" => (int)Species.Sirfetchd,
-            _ => -1,
-        };
+        // Eventually we'll refactor this once Dictionary<string, ushort> supports ReadOnlySpan<char> fetching in NET 9 runtime/#27229
+        var hash = string.GetHashCode(speciesName);
+        var dict = SpeciesDict[language];
+        if (!dict.TryGetValue(hash, out species))
+            return false;
+        // Double check the species name
+        var arr = SpeciesLang[language];
+        var expect = arr[species];
+        return speciesName.SequenceEqual(expect);
     }
 }

PKHeX.Core/Saves/SAV5.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
@@ -39,7 +40,7 @@ public abstract class SAV5 : SaveFile, ISaveBlock5BW, IEventFlag37
     public override int MaxBallID => Legal.MaxBallID_5;
     public override int MaxGameID => Legal.MaxGameID_5; // B2
 
-    protected SAV5(int size) : base(size)
+    protected SAV5([ConstantExpected] int size) : base(size)
     {
         Initialize();
         ClearBoxes();

PKHeX.Core/Saves/SAV_STADIUM.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Buffers.Binary;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 
 namespace PKHeX.Core;
@@ -40,7 +41,7 @@ public abstract class SAV_STADIUM : SaveFile, ILangDeviantSave
         IsPairSwapped = true;
     }
 
-    protected SAV_STADIUM(bool japanese, int size) : base(size)
+    protected SAV_STADIUM(bool japanese, [ConstantExpected] int size) : base(size)
     {
         Japanese = japanese;
         OT = SaveUtil.GetSafeTrainerName(this, (LanguageID)Language);

PKHeX.Core/Saves/Substructures/Inventory/Pouch/InventoryPouch3.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
@@ -7,7 +8,7 @@ public sealed class InventoryPouch3 : InventoryPouch
 {
     public uint SecurityKey { private get; set; } // = 0 // Gen3 Only
 
-    public InventoryPouch3(InventoryType type, IItemStorage info, int maxCount, int offset, int size)
+    public InventoryPouch3(InventoryType type, IItemStorage info, int maxCount, int offset, [ConstantExpected] int size)
         : base(type, info, maxCount, offset, size)
     {
     }

PKHeX.Core/Saves/Substructures/Inventory/Pouch/InventoryPouch3GC.cs

@@ -1,11 +1,12 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
 
 public sealed class InventoryPouch3GC : InventoryPouch
 {
-    public InventoryPouch3GC(InventoryType type, IItemStorage info, int maxCount, int offset, int size)
+    public InventoryPouch3GC(InventoryType type, IItemStorage info, int maxCount, int offset, [ConstantExpected] int size)
         : base(type, info, maxCount, offset, size)
     {
     }

PKHeX.Core/Saves/Substructures/Inventory/Pouch/InventoryPouch7b.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
@@ -13,7 +14,7 @@ public sealed class InventoryPouch7b : InventoryPouch
 
     public override InventoryItem7b GetEmpty(int itemID = 0, int count = 0) => new() { Index = itemID, Count = count };
 
-    public InventoryPouch7b(InventoryType type, IItemStorage info, int maxCount, int offset, int size) : base(type, info, maxCount, offset, size) { }
+    public InventoryPouch7b(InventoryType type, IItemStorage info, int maxCount, int offset, [ConstantExpected] int size) : base(type, info, maxCount, offset, size) { }
 
     public override void GetPouch(ReadOnlySpan<byte> data)
     {

PKHeX.Core/Saves/Substructures/Inventory/Pouch/InventoryPouch8.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using static System.Buffers.Binary.BinaryPrimitives;
 
 namespace PKHeX.Core;
@@ -11,7 +12,7 @@ public sealed class InventoryPouch8 : InventoryPouch
     public bool SetNew { get; set; }
     private int[] OriginalItems = Array.Empty<int>();
 
-    public InventoryPouch8(InventoryType type, IItemStorage info, int maxCount, int offset, int size) : base(type, info, maxCount, offset, size) { }
+    public InventoryPouch8(InventoryType type, IItemStorage info, int maxCount, int offset, [ConstantExpected] int size) : base(type, info, maxCount, offset, size) { }
 
     public override InventoryItem8 GetEmpty(int itemID = 0, int count = 0) => new() { Index = itemID, Count = count };
 

PKHeX.Core/Saves/Substructures/Inventory/Pouch/InventoryPouchGB.cs

@@ -1,10 +1,11 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 namespace PKHeX.Core;
 
 public sealed class InventoryPouchGB : InventoryPouch
 {
-    public InventoryPouchGB(InventoryType type, IItemStorage info, int maxCount, int offset, int size)
+    public InventoryPouchGB(InventoryType type, IItemStorage info, int maxCount, int offset, [ConstantExpected] int size)
         : base(type, info, maxCount, offset, size)
     {
     }

PKHeX.Core/Util/Util.cs

@@ -221,20 +221,4 @@ public static partial class Util
         int index = input.IndexOf(c);
         return index < 0 ? input : input[..index];
     }
-
-    public static Dictionary<string, int>[] GetMultiDictionary(IReadOnlyList<IReadOnlyList<string>> nameArray, int start)
-    {
-        var result = new Dictionary<string, int>[nameArray.Count];
-        for (int i = 0; i < result.Length; i++)
-            result[i] = GetDictionary(nameArray[i], start);
-        return result;
-    }
-
-    private static Dictionary<string, int> GetDictionary(IReadOnlyList<string> names, int start)
-    {
-        var result = new Dictionary<string, int>(names.Count - start);
-        for (int i = start; i < names.Count; i++)
-            result.Add(names[i], i);
-        return result;
-    }
 }

PKHeX.WinForms/Controls/PKM Editor/PKMEditor.cs

@@ -1751,12 +1751,10 @@ public sealed partial class PKMEditor : UserControl, IMainEditor
 
     private void ValidateMovePaint(object? sender, DrawItemEventArgs e)
     {
-        if (sender is null || e.Index < 0)
+        if (sender is not ComboBox cb || e.Index < 0 || cb.Items[e.Index] is not ComboItem item)
             return;
 
-        var cb = (ComboBox)sender;
-        var item = cb.Items[e.Index];
-        var (text, value) = (ComboItem)item;
+        var (text, value) = item;
         var valid = LegalMoveSource.Info.CanLearn((ushort)value) && !HaX;
 
         var current = (e.State & DrawItemState.Selected) != 0;

PKHeX.WinForms/Subforms/Save Editors/Gen1/SAV_EventReset1.cs

@@ -28,7 +28,7 @@ public partial class SAV_EventReset1 : Form
             var specName = split[0][G1OverworldSpawner.FlagPropertyPrefix.Length..];
 
             // convert species name to current localization language
-            var species = SpeciesName.GetSpeciesID(specName);
+            SpeciesName.TryGetSpecies(specName, (int)LanguageID.English, out var species);
             var pkmname = GameInfo.Strings.specieslist[species];
 
             if (split.Length != 1)

PKHeX.WinForms/Subforms/Save Editors/Gen8/SAV_PokedexLA.cs

@@ -235,9 +235,13 @@ public partial class SAV_PokedexLA : Form
         {
             var selectedForm = Dex.GetSelectedForm(species);
             CB_DisplayForm.SelectedIndex = 0;
-            for (var i = 0; i < CB_DisplayForm.Items.Count; ++i)
+            var items = CB_DisplayForm.Items;
+            for (var i = 0; i < items.Count; ++i)
             {
-                if (((ComboItem)CB_DisplayForm.Items[i]).Value != selectedForm)
+                var item = items[i];
+                if (item is not ComboItem cb)
+                    throw new Exception("Invalid item type");
+                if (cb.Value != selectedForm)
                     continue;
 
                 CB_DisplayForm.SelectedIndex = i;

PKHeX.WinForms/Util/WinFormsTranslator.cs

@@ -203,7 +203,7 @@ public static class WinFormsTranslator
             var argCount = constructors[0].GetParameters().Length;
             try
             {
-                var _ = (Form?)Activator.CreateInstance(t, new object[argCount]);
+                _ = (Form?)Activator.CreateInstance(t, new object[argCount]);
             }
             // This is a debug utility method, will always be logging. Shouldn't ever fail.
             catch

Tests/PKHeX.Core.Tests/Util/StringQualityTests.cs

@@ -22,6 +22,28 @@ public class StringQualityTests
         CheckMetLocations(language);
         CheckItemNames(language);
         CheckMoveNames(language);
+        CheckSpeciesNames(language);
+    }
+
+    /// <summary>
+    /// Checks for duplicate hashes in the species list.
+    /// </summary>
+    /// <remarks>
+    /// Uses hashes instead of strings as other logic uses dictionaries of hashes.
+    /// </remarks>
+    private static void CheckSpeciesNames(string language)
+    {
+        var strings = GameInfo.GetStrings(language);
+        var arr = strings.specieslist;
+        var hashset = new HashSet<int>(arr.Length);
+        var duplicates = new List<string>(0);
+        foreach (var line in arr)
+        {
+            var hash = line.GetHashCode();
+            if (!hashset.Add(hash))
+                duplicates.Add(line);
+        }
+        duplicates.Count.Should().Be(0, "expected no duplicate strings.");
     }
 
     private static void CheckMoveNames(string language)