The Pokemon Go blog has been updated with the big news that Trainer Battles are finally coming to the game. Later in December, players will be able to challenge friends or any other Trainer in the area. Each player will sport a team of three Pokemon that will duke it out to see which one survives the encounter. Win or lose, "both participants will receive great rewards, including a chance at rare Evolution items".
Players will be divided into Trainer Battle Leagues "which determines the CP limit" for participating Pokemon.
Battles are fast-paced and real-time, so don’t expect to wait your turn! Your selected team of Pokémon will be able to execute both their Fast Attack and Charged Attack moves. In preparation for battle, you’ll even be able to use Stardust and Candy to unlock a bonus Charged Attack for your Pokémon. Timing is important! If you use your head and keep an eye on your opponent’s moves, you may be able to deploy a Protect Shield to save your Pokémon from critical damage. But you only have a limited number of these shields before your Pokémon will be left defenseless.
The best part is that players can challenge Friends and Best Friends from any distance, though battles between other Trainers will need to be nearby one another.
Read the details on the Pokemon Go site.