Players start with one Rental Pass, but unlock more as the game progresses.
The design of the Rental Pass cannot be changed, nor can the body type of the Trainer on it, but everything else about the pass can be customized. Pokémon can even be moved between Rental Passes. All rental Pokémon are level 50 and can be Shiny.
Rental Passes are primarily used in the Gateway Colosseum, which only allows Rental Passes to be entered. Once the Trade Battle Mode is unlocked, Rental Passes can be further customized as after every battle in Trade mode, one can exchange a Pokémon they used for a Pokémon the opponent used and if the Colosseum Challenge is a success, the modified Rental Pass remains with its altered team.
Upon starting for the first time, players are allowed to choose one of the following two passes representing the first and fourth generations, respectively: