Pasio is an artificial island where each Trainer has one trusted Pokémon partner. Together, the Trainer and their Pokémon are known as a sync pair, and they participate in 3-on-3 team battles.

The Pokémon Masters League (PML) is a tournament held on Pasio. It features Gym Leaders, Elite Four members, Champions, and other all-stars from every region, who come together to form teams and participate in intense, 3-on-3 team battles.

To participate in the PML, players must battle PML Leaders all over Pasio to obtain five badges. You, as the main character, will team up with Pikachu to form a sync pair, sharing in many adventures as you strive to qualify for the PML.