Most of the time, players will be catching Pokemon or completing Research Tasks in Pokemon GO. Unlike mainline Pokemon games, trainer battles aren't nearly as common. Instead, players will be using their Pokemon in raids, gym battles, and fighting Team GO Rocket. Although the battle system works differently from the main games, they're still vital in earning rewards used for powering up Pokemon.
Team Rocket still serves as the primary antagonist in Pokemon GO. Players are likely to run into a Rocket Grunt at a PokeStop. They can also be challenged by interacting with a Rocket Balloon on the overworld map. Those looking to challenge elite Team GO Rocket members will need the help of the Rocket Radar.
Mysterious Components and Rocket Radars
Once players reach level 8, they can battle Team GO Rocket Grunts at black/darkened PokeStops. Defeating them will return a PokeStop to its blue color, allowing players to spin the PokeStop disc for more items. They can also challenge Team Rocket to an immediate rematch if they're defeated. However, they'll need to use Revives and Potions to heal up their team since Pokemon GO does not automatically restore a Pokemon's HP outside of battle.
Each time a Team GO Rocket Grunt is defeated, players will earn an item called a Mysterious Component. After defeating six Grunts, the Mysterious Components will create a Rocket Radar. This item is used to track down Team Rocket Leaders: Cliff, Arlo, and Sierra. As most players would expect, the Team Rocket Leaders are a lot tougher than their lower-ranking teammates. Furthermore, their team may change after they've been beaten once or twice. Fighting a Team Rocket Leader will "consume" a Rocket Radar. To get another one, players can either defeat 6 more Grunts, or they can buy one from the Shop for 200 PokeCoins. Since PokeCoins can be hard to come by, it's recommended to save the in-game currency for more useful items.
There's also a Rocket Radar called the Super Rocket Radar. This can't be obtained by defeating the Grunts or even the Leaders. The Super Rocket Radar could only be obtained through Special Research or Timed Research. By using the Super Rocket Radar, players could challenge Giovanni and his team.
Players will have a chance of snagging one of Team GO Rocket's Shadow Pokemon if they manage to win. Unfortunately, players can't choose which Shadow Pokemon to catch. Shadow Pokemon are caught using Premier Balls, which players will get a set amount based on how well their battle went against Team GO Rocket. If players only have one surviving Pokemon by the end of the battle, they'll have fewer chances (i.e: Premier Balls) at catching the Shadow Pokemon.
Rocket Balloons
The other way of battling Team GO Rocket is by keeping an eye out for Rocket Balloons. These will appear as a circular shadow on the overworld map. Players will need to zoom out in order to tap the balloon icon. This will trigger a battle with a Team GO Rocket Grunt or a Team Rocket Leader, depending on whether players have a Rocket Radar.
There isn't a way to trigger Rocket Balloons from appearing. However, they'll appear frequently throughout the day, and players don't need to be in motion for one to spawn on the map. Some Timed Events in Pokemon GO will increase the frequency of Rocket Balloons.
When speaking to a Team GO Rocket Grunt, their dialogue will allude to what type of team they have. For example, if a Grunt says, "Coiled and ready to strike!" they're going to have a team of Poison-type Pokemon. Thus, it's not recommended to bring pure Grass-type or Fairy-type Pokemon to the battle. The only exception are the Grunts that say, "Don’t bother – I’ve already won./Get ready to be defeated!/Winning is for winners!". They don't specify a specific type of Pokemon but instead have a more balanced team.
Pokemon GO is available for mobile devices.