Do you mean Black 2 exclusive Pokemon or all the Pokemon in Black 2?
In any case:
The Serebii Pokedex lists the Pokemon that are version exclusive as well, you just need to look at the Wild Location notes.
List of version exclusive Pokemon
Though, I should say that in your game, you can only get 1 starter (obviously), so if you want the other 2 starter Pokemon, you will have to trade for them.