According to the announcement on Niantic’s website, “Beginning this month, Trainer Battles will allow you to challenge a friend or another Trainer at any time! Challenge another Trainer using a Battle Code, assemble a team of three Pokémon, and see who comes out on top! When Trainer Battles are completed, both participants will receive great rewards, including a chance at rare Evolution items.”
The company does not state when exactly the feature will be going live, but the mention of “this month” suggests that it should be out in the next few days or weeks. Niantic’s announcement also reveals additional details about the upcoming feature, such as how players need to compete in the same Trainer Battle League to ensure an even playing field.
These battles are also done in real-time, meaning that unlike going up against a computer like on the regular Pokemon, it will not be turn-based. Trainer battles can only be initiated when players are near each other, but remote battles can be done if you’re Ultra or Best Friends.