The only PvP (player vs. player) system is the Gym system. In the area where we live, some places become PokeStops where you can collect eggs and Poke Balls, some places become Gyms. When we beat a Gym, our team can take over it and use the Gym to earn PokeCoins. Of course, we also need to defend the Gym from other teams’ attack. And before we take over a Gym, we need to choose a team.
How to Join a Team
When a player reaches level 5 and click the nearby Gym, Dr. Willow will appear and allow the player to choose a team. Below are teams available.
Gym Guide
Attack and Defend Gyms
If we are lucky enough, we may come across an unoccupied Gym marked by white. In this case, we can click the icon in the lower left corner to put our Pokemon in the Gym in order to claim the Gym. Subsequently, the Gym will be marked the same color of our team. The Pokemon in this Gym will appear above the Gym. Please note that only Pokemon with the max HP can be put into the Gym for the purpose of defending.
Attack Moves
Once players enter the Gym battle interface, the background will become the battlefield. When the countdown ends, players can attack the Pokemon that are used to defend the Gym. The energy bar will be constantly filled. Once the energy bar is full, players can press the phone screen to use Pokemon’s unique attack moves. When the charge is completed, the moves will be automatically used. Players can also slide left or right to dodge. If the timing is proper, a dodge message will pop up, and Pokemon won’t be hurt.
Super Effective and Not So Effective
When Pokemon perform attacks of certain types or elements or get attacked by certain types, if the damage is effective, then it will double the damage. A Super Effective message will pop up. If the damage Pokemon receive is just average, the damage will only be half of the original one, and a Not So Effective message will pop up
Source from: http://www.pokemongoaccountbuy.com/news/10–pokemon-go-guide-to-gym-and-how-to-join-a-team
Buy Pokemon Go Accounts and Rare Pokemon Online 