The original 001-493 Pokemon. (Most likely going to be expanded for Generation V.)
List of National Pokemon
A custom region for Fakemon. It's completely optional because after Sinnoh or any region you have the option of "retiring" and not having to go any further.
List of Kyoto Fakemon
Yes, it is possible to catch Digimon (that don't have weapons) and they have rounded stats to similar Pokemon.
List of National Digimon
For the first time ever you can and probably will want to catch the glitch Pokemon just to add a little bit more fun to the game.
List of National Glitch Pokemon
A Scientist recently discovered how certain Pokemons' DNA can be combined to form a new Pokemon.
List of National Fusion Pokemon
These Pokemon can show up with a different sprite, and possibly have different typing, or movesets.
Each is apart of their respective lists.