 A select group of species cannot breed at all, which includes all Legendary Pokémon, all Ultra Beasts, most Mythical Pokémon, Nidorina and Nidoqueen (but not Nidoran♀), Unown, and all "baby" Pokémon.This is called the "Undiscovered" Egg Group.Although some Legendary Pokémon have genders, they still cannot breed.