diff --git a/PKHeX.Core/Legality/Checks.cs b/PKHeX.Core/Legality/Checks.cs
index 2b216791a..3aea33f94 100644
--- a/PKHeX.Core/Legality/Checks.cs
+++ b/PKHeX.Core/Legality/Checks.cs
@@ -2082,6 +2082,11 @@ private void VerifyForm()
                         AddLine(Severity.Invalid, V310, CheckIdentifier.Form);
                         return;
                     }
+                    if (pkm.AltForm != 0 ^ Type == typeof(MysteryGift)) // Formes are not breedable
+                    {
+                        AddLine(Severity.Invalid, string.Format(V304, 0, pkm.AltForm), CheckIdentifier.Form);
+                        return;
+                    }
                     break;
                 case 664: // Scatterbug
                 case 665: // Spewpa