Add bypass for alpha move purchased

ty @Atrius97 for finally nailing the repro on this

Co-Authored-By: Atrius97 <39707481+Atrius97@users.noreply.github.com>
Co-Authored-By: Lusamine <30205550+Lusamine@users.noreply.github.com>

PKHeX.Core/Legality/Encounters/EncounterSlot/EncounterSlot8a.cs

@@ -141,15 +141,19 @@ public sealed record EncounterSlot8a : EncounterSlot, IAlpha, IMasteryInitialMov
         if (pkm is not IMoveShop8Mastery p)
             return true; // Can't check.
 
-        Span<int> moves = stackalloc int[4];
+        bool allowAlphaPurchaseBug = Area.Type is not SlotType.OverworldMMO; // Everything else Alpha is pre-1.1
         var level = pkm.Met_Level;
         var index = PersonalTable.LA.GetFormIndex(Species, Form);
-        var mastery = Legal.MasteryLA[index];
         var learn = Legal.LevelUpLA[index];
-        ushort alpha = 0;
+        ushort alpha = pkm is PA8 pa ? pa.AlphaMove : (ushort)0;
+        if (!p.IsValidPurchasedEncounter(learn, level, alpha, allowAlphaPurchaseBug))
+            return false;
+
+        Span<int> moves = stackalloc int[4];
+        var mastery = Legal.MasteryLA[index];
         if (pkm is PA8 { AlphaMove: not 0 } pa8)
         {
-            moves[0] = alpha = pa8.AlphaMove;
+            moves[0] = pa8.AlphaMove;
             learn.SetEncounterMovesBackwards(level, moves, 1);
         }
         else
@@ -157,7 +161,7 @@ public sealed record EncounterSlot8a : EncounterSlot, IAlpha, IMasteryInitialMov
             learn.SetEncounterMoves(level, moves);
         }
 
-        return p.IsValidMasteredEncounter(moves, learn, mastery, level, alpha);
+        return p.IsValidMasteredEncounter(moves, learn, mastery, level, alpha, allowAlphaPurchaseBug);
     }
 
     private OverworldParam8a GetParams()

PKHeX.Core/Legality/Encounters/EncounterStatic/EncounterStatic8a.cs

@@ -122,17 +122,21 @@ public sealed record EncounterStatic8a(GameVersion Version) : EncounterStatic(Ve
         if (pkm is not IMoveShop8Mastery p)
             return true;
 
-        Span<int> moves = stackalloc int[4];
+        const bool allowAlphaPurchaseBug = true; // Everything else Alpha is pre-1.1
         var level = pkm.Met_Level;
         var index = PersonalTable.LA.GetFormIndex(Species, Form);
         var learn = Legal.LevelUpLA[index];
+        if (!p.IsValidPurchasedEncounter(learn, level, alpha, allowAlphaPurchaseBug))
+            return false;
+
+        Span<int> moves = stackalloc int[4];
         var mastery = Legal.MasteryLA[index];
         if (Moves.Count != 0)
             moves = (int[])Moves;
         else
             learn.SetEncounterMoves(level, moves);
 
-        return p.IsValidMasteredEncounter(moves, learn, mastery, level, alpha);
+        return p.IsValidMasteredEncounter(moves, learn, mastery, level, alpha, allowAlphaPurchaseBug);
     }
 
     protected override void SetEncounterMoves(PKM pk, GameVersion version, int level)

PKHeX.Core/Legality/Encounters/Generator/Specific/EncounterStaticGenerator.cs

@@ -93,7 +93,7 @@ namespace PKHeX.Core
             }
         }
 
-        internal static EncounterStatic7 GetVCStaticTransferEncounter(PKM pkm, IEncounterTemplate enc, IReadOnlyList<EvoCriteria> chain)
+        internal static EncounterStatic7 GetVCStaticTransferEncounter(PKM pkm, IEncounterTemplate enc, ReadOnlySpan<EvoCriteria> chain)
         {
             // Obtain the lowest evolution species with matching OT friendship. Not all species chains have the same base friendship.
             var met = (byte)pkm.Met_Level;
@@ -113,7 +113,7 @@ namespace PKHeX.Core
             }
         }
 
-        private static int GetVCSpecies(IReadOnlyList<EvoCriteria> chain, PKM pkm, int max)
+        private static int GetVCSpecies(ReadOnlySpan<EvoCriteria> chain, PKM pkm, int max)
         {
             int species = pkm.Species;
             foreach (var z in chain)

PKHeX.Core/PKM/Interfaces/IMoveShop8.cs

@@ -21,7 +21,36 @@ public interface IMoveShop8Mastery : IMoveShop8
 
 public static class MoveShop8MasteryExtensions
 {
-    public static bool IsValidMasteredEncounter(this IMoveShop8Mastery shop, Span<int> moves, Learnset learn, Learnset mastery, int level, ushort alpha)
+    public static bool IsValidPurchasedEncounter(this IMoveShop8 shop, Learnset learn, int level, ushort alpha, bool allowPurchasedAlpha)
+    {
+        var permit = shop.MoveShopPermitIndexes;
+        var current = shop.MoveShopPermitFlags;
+        for (int i = 0; i < current.Length; i++)
+        {
+            if (!current[i])
+                continue;
+
+            if (!shop.GetPurchasedRecordFlag(i))
+                continue;
+
+            var move = permit[i];
+
+            // Can only purchase a move if it is not already in the available learnset.
+            var learnLevel = learn.GetMoveLevel(move);
+            if (learnLevel <= level)
+                return false;
+
+            // Can only purchase an Alpha Move if it was pre-1.1 patch.
+            if (move == alpha && allowPurchasedAlpha)
+                continue;
+
+            return false;
+        }
+
+        return true;
+    }
+
+    public static bool IsValidMasteredEncounter(this IMoveShop8Mastery shop, Span<int> moves, Learnset learn, Learnset mastery, int level, ushort alpha, bool allowPurchasedAlpha)
     {
         foreach (var move in moves)
         {
@@ -46,7 +75,13 @@ public static class MoveShop8MasteryExtensions
             }
             else
             {
-                if (p || !m)
+                // Pre 1.1 patch, players could purchase the Alpha Move from the move shop.
+                // After the patch, the Alpha Move is considered purchased (even without the flag).
+                // Players won't be able to waste money after the patch :)
+                // For legality, allow the Alpha Move to be flagged as Purchased if it was a pre-patch capture.
+                if (p && (move != alpha || !allowPurchasedAlpha))
+                    return false;
+                if (!m)
                     return false;
             }
         }