Breeding stats are information that is relevant to breeding Pokémon. These are:
Egg groups - A Pokémon can belong to either one or two egg groups.
Gender ratios - The likelihood of finding a Pokémon of a particular gender in the wild.
Number of steps required to hatch an egg.
Egg groups and gender ratios determine which Pokémon are able to breed with each other. A Pokémon can only successfully breed with another Pokémon if the two are opposite genders and share an egg group. The exceptions are the Undiscovered group which cannot breed at all, and the Ditto group which can breed with any other group that can breed.