https://techcrunch.com/2018/12/12/pokemon-go-pvp-release-date/

Last week we did a deep dive on how Pokémon GO’s new (and long overdue) player-versus-player battle system would work. The only thing we didn’t know at the time was when, exactly, it would actually start rolling out.

Just a few days ago, Niantic started shipping an update to the app that contained everything required for PvP, but they’d yet to actually flip the switch to turn it on. According to a tweet that just went live from the Pokémon GO account, it seems said switches have just been flipped: