Pokémon GO has launched the Preview Cup (Experimental), a limited format that serves as the only place to try out its new PvP battle system. The mode gives players an early look at updated mechanics and balance changes before any wider rollout, effectively turning competitive matches into a live test environment. It is a clear sign the developers are experimenting with how battles feel and flow, while gathering feedback from active players to shape future updates to the game’s PvP scene.
Source: Official Pokémon GO blog and Pokemon.com