Egg Groups

Egg Groups are classifications of Pokémon that determine whether species of Pokémon are able to breed with each other. For the most part, Pokémon that share an Egg Group are able to breed with each other if they are of opposite genders. However, Pokémon in the Undiscovered Egg Group cannot breed at all, while any Pokémon can breed with Ditto besides Pokémon in the Undiscovered Egg Group.