The developers of Pokémon GO, Niantic, announced via a post on the Pokémon GO website that an online version of the Trainer Battle system will be launching early 2020 called GO Battle League.
Much like the mainline series Pokémon game, the GO Battle League will have an online matchmaking system based on your current rank in the league.
To gain entry to the GO Battle League, trainers must walk with their Pokémon in real life, though the full details of this haven’t been revealed at this time.