Why are Skrelp and Clauncher able to be caught in both ORAS and XY, but Flabébé can’t be caught in ORAS?

Question

Are these the only two Pokémon that can be caught here, if so why ?

Comments

Game Freak logic

Answer 1

It’s because not all Gen 6 Pokémon can be in ORAS. In fact, most of the Gen 6 Pokémon don’t appear in ORAS. This was partly to encourage trade more between generations as well as have people buy Pokémon XY and pokebank.