Which Pokémon Have Unique Egg Group Combinations?

Breeding Pokémon is a favorite pass-time of many trainers out there, but to successfully do so you'll need to master the Egg Groups, which limit the possible pairings a Pokémon can have! But since Pokémon can have more than one Egg Group at a time that can lead certain pairings to be unique to one evolutionary line, so let's see which combinations of Egg Groups are only accessible with one Pokémon!