Each trainer travels with one companion Pokémon, and together, they're known as sync pairs. You need to go on a journey with the trainers you team up with and earn badges to qualify for the Pokémon Masters League. When you do fight, you'll find yourself in 3-vs-3 real-time battles. The Pokémon Company is working with DeNA, the mobile developer behind Super Mario Run and Fire Emblem Heroes, for this particular project. They're bound to reveal a more specific date in the near future, barring any delays to the game's rollout.