Add nidoran/volbeat-illumise gen3/4 gender check

Closes #4356
adds check
revises egg->pk* logic to generate a valid pid for this case

PKHeX.Core/Legality/Breeding.cs

@@ -18,11 +18,33 @@ public static class Breeding
         (int)Volbeat => true,
         (int)Illumise => true,
 
-        (int)Indeedee => true, // male/female
+        (int)Indeedee => true, // male/female form
 
         _ => false,
     };
 
+    /// <summary>
+    /// Species that are determined when the egg is received.
+    /// </summary>
+    public static bool IsGenderSpeciesDetermination(ushort species) => species switch
+    {
+        (int)NidoranF => true,
+        (int)NidoranM => true,
+
+        (int)Volbeat => true,
+        (int)Illumise => true,
+
+        _ => false,
+    };
+
+    /// <summary>
+    /// Checks if the species <see cref="ec"/> is valid for the <see cref="gender"/> if originated from Gen3/4 daycare eggs.
+    /// </summary>
+    /// <param name="ec">Encryption Constant</param>
+    /// <param name="gender">Gender</param>
+    /// <returns>True if valid</returns>
+    public static bool IsValidSpeciesBit34(uint ec, byte gender) => gender != (ec & 0x8000) >> 15; // 1 = Male, 0 = Female, valid if different from Gender value.
+
     /// <summary>
     /// Checks if the <see cref="species"/> can be born with inherited moves from the parents.
     /// </summary>

PKHeX.Core/Legality/Encounters/Templates/Shared/EncounterEgg.cs

@@ -134,6 +134,15 @@ public sealed record EncounterEgg(ushort Species, byte Form, byte Level, byte Ge
             pk.SetPIDGender(gender);
             pk.Gender = gender;
             pk.SetPIDNature(nature);
+            if (pk.Format is 3 or 4 && Breeding.IsGenderSpeciesDetermination(pk.Species))
+            {
+                while (!Breeding.IsValidSpeciesBit34(pk.EncryptionConstant, gender))
+                {
+                    // Try again.
+                    pk.SetPIDGender(gender);
+                    pk.SetPIDNature(nature);
+                }
+            }
             pk.Nature = nature;
             pk.RefreshAbility(pk.PIDAbility);
         }

PKHeX.Core/Legality/Verifiers/PIDVerifier.cs

@@ -126,6 +126,11 @@ public sealed class PIDVerifier : Verifier
         // Gen3-5 => Gen6 have PID==EC with an edge case exception.
         if (Info.Generation is 3 or 4 or 5)
         {
+            if (Info.Generation is 3 or 4 && Info.EncounterMatch is EncounterEgg egg && Breeding.IsGenderSpeciesDetermination(egg.Species))
+            {
+                if (!Breeding.IsValidSpeciesBit34(pk.EncryptionConstant, pk.Gender))
+                    data.AddLine(GetInvalid(LPIDGenderMismatch, CheckIdentifier.EC));
+            }
             VerifyTransferEC(data);
             return;
         }