Pokémon Battle Revolution 2/Stadium U
The Gen V Battle Sim is long overdue and it HAS to happen. Perhaps include an RPG mode akin to Colosseum, but otherwise include loads of new bits to battle, perhaps duplicate the World Tournament feature from Black 2 & White 2. Plus, as it's coming out close to the end of Gen V, I can see them doing Nintendo style DLC for say £15 where it will add the Gen VI Pokémon to teams of various people, update others with the new moves and the new battle mechanics, add new colosseums etc. essentially making it a new game which they can then also package and sell if they do so wish