[[File:GO Professors Assistants.png|300px|thumb|
Spark, Blanche, and Candela]]
After the player reaches level 5, they can choose a team by tapping a Gym. There are three teams: Team Instinct (yellow) whose leader is Spark, Team Mystic (blue) whose leader is Blanche, and Team Valor (red) whose leader is Candela. A Gym can only be controlled by one team at a time. If a Gym is controlled by the player's team, they can train at it and add one of their own Pokémon to defend it. If a Gym is controlled by a rival team, the player can battle it to decrease its Prestige; when a Gym's Prestige reaches zero, the player can claim it for their own team.