The next big Pokemon game is a direct sequel to Pokemon Black and Pokemon White, aptly titled "Pokemon Black 2 and Pokemon White 2." The legendary monsters the games feature appear to be a mix of a couple of the creatures from Black and White, so why not go for the gusto? Any older legendaries should be up for grabs!
I'm not too sure how I feel about these games releasing for the DS. Wouldn't a big game like this sell the 3DS like mad? Every child will be clamouring for it, so it seems like a wasted business opportunity to me.
I suppose the game itself will sell more this way, though, considering there are about four hundred billion DS systems out there.