Dang it. It looks awesome. This game is going to use the DS as a controller. Each player will have to use his/her own DS, and even more: Players can customize their trainer in the game.
The game takes place in Pokétopia, where you have to beat the 10 colosseums, and you can unlock more by beating the previous ones.

DS Battle Mode (requires DS systems for all players, sold separately): Four players can gather together and battle while using Pokémon from their Pokémon Diamond and Pokémon Pearl video games. All players use the DS as their controller in this mode, and it uses the same battle interface found in Pokémon Diamond and Pokémon Pearl.

Players can customize their Trainers in the game.

Nintendo DS Battle Mode: This multiplayer mode is for those who also own Pokémon Diamond or Pokémon Pearl as well as Nintendo DS systems. Four players can get together and battle while using their very own Pokémon from their Pokémon Diamond and Pokémon Pearl games. All players use the DS as a controller in this mode. The same battle interface that is used in Pokémon Diamond and Pokémon Pearl is used while battling with friends.

Battle Passes and Trainer Customization: Players can create and customize their own Battle Pass by transferring their favorite Pokémon onto the Pass. They can then save the Battle Pass to their Wii Remote and take it to a friend’s house to battle with them

Vermillion via nintendorevolution.ca »