What games would I need to finish the National Pokédex in Pokémon XY?

Question

What games do I need? I have two 3DS and X, Y, Omega Ruby, and I'm gonna get Alpha Sapphire.

Answer 1

You can complete the entire National Pokedex, (bar Mythicals,) with all four Gen VI games. This is well-known and extremely convenient. Now that the GTS is gone, X, Y, Omega Ruby, and Alpha Sapphire are required.

Source

Hope this helps!