It's really just an enhancement for Pokémon Diamond/Pearl.
Pokémon Battle Revolution is already out in Japan and it’s this very version that I played at GDC; an English translation is not finished yet. Pokémon Battle Revolution is not exactly a real game in itself and there is no single player mode. Like Pokémon Colosseum and Pokémon Stadium, Battle Revolution allows players to battle with Pokémon in their full 3-D glory on the TV screen. Of course this glory isn’t particularly notable as the polygon counts for the Pokémon have not increased significantly over the GameCube version. The only notable graphical enhancement is a soft, shiny lighting effect that seems to make everything glisten, which also appeared in the Super Mario Galaxy E3 demo.
Though the Wii remote can be used, the game is intended to be played through the Nintendo DS with a copy of the upcoming Pokémon Diamond or Pearl. Pokémon raised on the handheld can be brought to the Wii for battle. Using the touch screen, players can select their Pokémons’ attacks and targets through a series of menus. Once everybody has finished their selections, the Pokémon battle it out on the TV screen using plenty of flashy elemental special effects. All communication is wireless, and basically, this is what GC-GBA connectivity ideally would have embodied.
Pokémon Battle Revolution is scheduled for a June 25 release in the US, not only ushering in Wii-DS connectivity, but also Wii online play.