I gotta go with X and Y.
There's been so much demand for a game with all the regions that it's getting really annoying. Do they not realize how much space that will take up? It definitely wouldn't be portable, that's for sure.
Typical demand comment i see:
"OMG their shood b a gaim with ALL the reejons and u cn catch ALL the pokemon and battl ALL the jim leeders and get ALL the badges and the eleet four is everyone u played as in the uther gaims, and the champeeon is Red!!! durr hurr, hurrie up nintendo!!!"
When I heard the rumor for Rainbow, I both thought "FAKE!" and "Finally, this will shut some of those people up." But we all knew it wasn't true. xD