Pokémon Rumble utilizes Toy Pokémon in lieu of regular Pokémon. The Toy Pokémon are brought to life by Wonder Keys. They can't grow stronger or evolve since they are toys, but can still learn moves and fight. Each Pokémon has a Power rating, similar to a level. They also can each learn two moves. One is assigned to the "2" Button and the other is assigned to the "1" button. When an opposing Toy Pokémon that isn't in a Battle Royale tournament is defeated, it will turn into Poké Dollars, or tip over and can be befriended by being touched. The active Pokémon can get switched out at anytime by pressing the "A" Button and choosing a Pokémon that has been befriended. Each Pokémon has its own HP, moves, etc. When a Pokémon faints, it is switched out for another Pokémon as long as there are still more Wonder Keys (the player starts a level with three, and lose one each time a Pokémon faints) and more Pokémon that haven't fainted. In the Battle Royale, the active Pokémon can't be switched out unless it faints.
There are several Terminals, each with its own designated Battle Royale tournament and levels. At first you can only get Pokémon from Kanto, but after you beat the game, you unlock Pokémon from Sinnoh.