Handle baby->mother parent fetch

Need to fix something with volbeat/nido for inheritance still.

PKHeX.Core/Legality/LearnSource/Sources/LearnSource2GS.cs

@@ -51,13 +51,14 @@ public ReadOnlySpan<ushort> GetEggMoves(ushort species, byte form)
     }
 
     // Present and not in Crystal:
-    // 001 (Bulbasaur) += Charm
     // 016 (Pidgey) += SteelWing
-    // 043 (Oddish) += Charm
     // 046 (Paras) += SweetScent
     // 083 (Farfetchd) += SteelWing
-    // 120 (Staryu) += AuroraBeam, Barrier, Supersonic
     // 142 (Aerodactyl) += SteelWing
+    // Inaccessible (no father in same egg group):
+    // 001 (Bulbasaur) += Charm
+    // 043 (Oddish) += Charm
+    // 120 (Staryu) += AuroraBeam, Barrier, Supersonic
     // 143 (Snorlax) += Charm
     // 238 (Smoochum) += LovelyKiss
 

PKHeX.Core/Legality/Moves/Breeding/ChainBreedLegality.cs

@@ -46,6 +46,7 @@ public static bool TryValidate(ushort species, byte form, GameVersion version, R
         // For male-only split breed species (Volbeat/Nidoran-M) in Gen 2-5, we need special validation:
         // All EGG moves must come from a single father.
         // Level-up moves don't need this restriction (can breed with Ditto).
+        // No cases of chain breeding combinations, so we can just check if a single father can pass all egg moves.
         var isMaleSplit = IsMaleOnlySplitBreed(species);
         if (isMaleSplit)
         {
@@ -239,18 +240,7 @@ private static bool CanSingleFatherPassAllMoves(ushort motherSpecies, byte mothe
                     continue;
 
                 // Check if this father can learn ALL the moves
-                bool canLearnAll = true;
-                foreach (var move in moves)
-                {
-                    if (move == 0)
-                        break;
-
-                    // Father must be able to learn this move as an egg move or level-up move
-                    if (CanFatherLearnMoveForEgg(fatherSpecies, fatherForm, move, learn))
-                        continue;
-                    canLearnAll = false;
-                    break;
-                }
+                var canLearnAll = CanFatherLearnAll(moves, fatherSpecies, fatherForm, learn);
                 if (!canLearnAll)
                     continue;
 
@@ -262,6 +252,20 @@ private static bool CanSingleFatherPassAllMoves(ushort motherSpecies, byte mothe
         return false; // No single father can pass all moves
     }
 
+    private static bool CanFatherLearnAll(ReadOnlySpan<ushort> moves, ushort fatherSpecies, byte fatherForm, ILearnSource learn)
+    {
+        foreach (var move in moves)
+        {
+            if (move == 0)
+                break;
+            // Father must be able to learn this move as an egg move or level-up move
+            if (CanFatherLearnMoveForEgg(fatherSpecies, fatherForm, move, learn))
+                continue;
+            return false;
+        }
+        return true;
+    }
+
     private static bool CanMotherAndFatherPassAllMoves(ushort motherSpecies, byte motherForm, GameVersion version, ReadOnlySpan<ushort> moves, out ChainBreedSummary summary)
     {
         // For male-only split breed species in Gen 6-7:
@@ -423,8 +427,7 @@ private static bool TryValidateBaseCounts(ushort eggSpecies, byte eggForm, GameV
 
             var suffix = moves.Slice(baseCount, inheritedCount);
             var suffixFlags = flags.Slice(baseCount, inheritedCount);
-            for (int i = 0; i < inheritedCount; i++)
-                inheritedMoves[i] = suffix[i];
+            suffix.CopyTo(inheritedMoves);
 
             if (TryResolveInheritedSources(eggSpecies, eggForm, version, inheritedMoves[..inheritedCount], suffixFlags, 0, visited, depth + 1, out summary))
                 return true;
@@ -463,6 +466,8 @@ private static bool TryResolveFather(ushort eggSpecies, byte eggForm, GameVersio
             return false;
 
         var mother = table[eggSpecies, eggForm];
+        if (mother.EggGroup1 == (int)EggGroup.Undiscovered && TryGetEvolvedMother(eggSpecies, eggForm, version, out var newMother))
+            mother = table[newMother.Species, newMother.Form];
 
         // If the egg species can't breed (baby Pokemon like Tyrogue), check if its evolutions can act as fathers
         if (mother.Genderless || mother.OnlyMale || mother.EggGroup1 == (int)EggGroup.Undiscovered)
@@ -496,9 +501,28 @@ private static bool TryResolveFather(ushort eggSpecies, byte eggForm, GameVersio
         return false;
     }
 
+    private static bool TryGetEvolvedMother(ushort eggSpecies, byte eggForm, GameVersion version, out (ushort Species, byte Form) newMother)
+    {
+        var tree = EvolutionTree.GetEvolutionTree(version.Context);
+        var evos = tree.Forward.GetEvolutions(eggSpecies, eggForm);
+        var pt = GameData.GetPersonal(version);
+
+        foreach (var (evoSpecies, evoForm) in evos)
+        {
+            var pi = pt[evoSpecies, evoForm];
+            if (pi.EggGroup1 == (int)EggGroup.Undiscovered)
+                continue;
+
+            newMother = (evoSpecies, evoForm);
+            return true;
+
+        }
+        newMother = default;
+        return false;
+    }
+
     private static bool TryResolveFatherViaEvolution(ushort eggSpecies, byte eggForm, GameVersion version, ReadOnlySpan<ushort> moves, Span<ChainQueryState> visited, int depth, out ChainBreedSummary summary)
     {
-        summary = default;
         var tree = EvolutionTree.GetEvolutionTree(version.Context);
         var evos = tree.Forward.GetEvolutions(eggSpecies, eggForm);
 
@@ -511,6 +535,7 @@ private static bool TryResolveFatherViaEvolution(ushort eggSpecies, byte eggForm
             return true;
         }
 
+        summary = default;
         return false;
     }
 

Tests/PKHeX.Core.Tests/Legality/ChainBreedLegalityTests.cs

@@ -32,6 +32,7 @@ public void DetectsInvalidChains(GameVersion version, Species species, params Mo
     [InlineData(HGSS, Mankey, Encore, Meditate, SmellingSalts)]
     [InlineData(GS, Chansey, DoubleEdge)] // via Jigglypuff (Level 39)
     [InlineData(Pt, Shellder, RapidSpin, IcicleSpear)]
+    [InlineData(R, Volbeat, HelpingHand)] // level up, breed with Illumise
     public void DetectsValidChains(GameVersion version, Species species, params Move[] movelist)
         => ValidateSimple(version, species, 0, movelist);
 
@@ -60,6 +61,7 @@ private static void ValidateSimple(GameVersion version, Species species, byte fo
 
     [Theory]
     [InlineData(HGSS, Mankey, 0, Smeargle, Encore, Meditate, SmellingSalts)]
+    [InlineData(E, Pichu, 0, Smeargle, Reversal, Encore, Wish, Present)] // via Pikachu mother
     public void DetectsValidChainSmeargle(GameVersion version, Species species, byte form, Species father, params Move[] movelist)
     {
         var moves = GetMoves(movelist);