Only Pokemon in the same breeding group can have an egg together when left to play at the Daycare Center, but how those breeding groups are decided, is beyond me. Why do I think the system is pure madness? Because the tiny Skitty can breed with the humongous Wailord!
I made this fanart because I feel bad for that poor, poor Skitty, and people should see the follies of irresponsible Pokemoon breeding!
Of course I'm just kidding, I love the breeding system, I love that all manor of creature lay eggs, and the most twisted match-ups are always my favorites.