Add gender changed azurill evo pokewalker edge case

Closes #2311 , thanks @SpiredMoth !

PKHeX.Core/Legality/Encounters/EncounterStatic.cs

@@ -337,7 +337,17 @@ public bool IsMatch(PKM pkm, int lvl)
             }
 
             if (Gender != -1 && Gender != pkm.Gender)
-                return false;
+            {
+                if (Species == (int)Core.Species.Azurill && Generation == 4 && Location == 233 && pkm.Gender == 0)
+                {
+                    if (PKX.GetGenderFromPIDAndRatio(pkm.PID, 0xBF) != 1)
+                        return false;
+                }
+                else
+                {
+                    return false;
+                }
+            }
             if (Form != pkm.AltForm && !SkipFormCheck && !Legal.IsFormChangeable(pkm, Species))
                 return false;
             if (EggLocation == Locations.Daycare5 && Relearn.Length == 0 && pkm.RelearnMoves.Any(z => z != 0)) // gen7 eevee edge case

PKHeX.Core/Legality/RNG/MethodFinder.cs

@@ -460,14 +460,35 @@ private static bool GetPokewalkerMatch(PKM pk, uint oldpid, out PIDIV pidiv)
             if (nature == 24) // impossible nature
                 return GetNonMatch(out pidiv);
 
-            uint pid = PIDGenerator.GetPokeWalkerPID(pk.TID, pk.SID, nature, pk.Gender, pk.PersonalInfo.Gender);
+            var gender = pk.Gender;
+            uint pid = PIDGenerator.GetPokeWalkerPID(pk.TID, pk.SID, nature, gender, pk.PersonalInfo.Gender);
 
             if (pid != oldpid)
-                return GetNonMatch(out pidiv);
+            {
+                if (!(gender == 0 && IsAzurillEdgeCaseM(pk, nature, oldpid)))
+                    return GetNonMatch(out pidiv);
+            }
             pidiv = new PIDIV {NoSeed = true, RNG = RNG.LCRNG, Type = PIDType.Pokewalker};
             return true;
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static bool IsAzurillEdgeCaseM(PKM pk, uint nature, uint oldpid)
+        {
+            // check for Azurill evolution edge case... 75% F-M is now 50% F-M; was this a F->M bend?
+            int spec = pk.Species;
+            if (spec != (int)Species.Marill && spec != (int)Species.Azumarill)
+                return false;
+
+            const int AzurillGenderRatio = 0xBF;
+            var gender = PKX.GetGenderFromPIDAndRatio(pk.PID, AzurillGenderRatio);
+            if (gender != 1)
+                return false;
+
+            var pid = PIDGenerator.GetPokeWalkerPID(pk.TID, pk.SID, nature, 1, AzurillGenderRatio);
+            return pid == oldpid;
+        }
+
         private static bool GetColoStarterMatch(PKM pk, uint top, uint bot, uint[] IVs, out PIDIV pidiv)
         {
             if (pk.Version != 15 || (pk.Species != 196 && pk.Species != 197))