Add formarg deferral for wild annihilape/kingambit

Closes #4167
Also add form bypass for Gen6 Deerling slot that changed form in SV.

PKHeX.Core/Legality/Encounters/Templates/Gen6/EncounterSlot6AO.cs

@@ -127,7 +127,14 @@ public sealed record EncounterSlot6AO(EncounterArea6AO Parent, ushort Species, b
             return false;
 
         if (evo.Form != Form && !IsRandomUnspecificForm)
-            return false;
+        {
+            if (Species is not ((ushort)Core.Species.Deerling or (ushort)Core.Species.Sawsbuck))
+                return false;
+
+            // Deerling can change between forms if imported to a future Gen8+ game.
+            if (pk.Format < 8 || evo.Form >= 4)
+                return false;
+        }
 
         return true;
     }

PKHeX.Core/Legality/Encounters/Templates/Gen9/EncounterSlot9.cs

@@ -238,7 +238,17 @@ public sealed record EncounterSlot9(EncounterArea9 Parent, ushort Species, byte
             if (m.RibbonMarkDawn && !CanSpawnAtTime(RibbonIndex.MarkDawn))
                 return EncounterMatchRating.DeferredErrors;
         }
+
+        if (IsFormArgDeferralRelevant(pk.Species) && pk is IFormArgument f)
+        {
+            bool isFormArg0 = f.FormArgument == 0;
+            bool mustBeZero = IsFormArgDeferralRelevant(Species);
+            if (isFormArg0 != mustBeZero)
+                return EncounterMatchRating.DeferredErrors;
+        }
         return EncounterMatchRating.Match;
+
+        static bool IsFormArgDeferralRelevant(ushort species) => species is (ushort)Core.Species.Kingambit or (ushort)Core.Species.Annihilape;
     }
     #endregion
 }