How to Battle
The only place to battle is in a Pokémon Gym, which we’ve already explained are vicious arenas of iniquity and horror, but if you’re dead set on progressing quickly in the game you’ll have to take part.
First and foremost, you’ll need to use the stardust and candies you’ve been collecting to power up your Pokémon so they’ll stand a chance of defeating the gym’s defending team. Additionally, there will likely be multiple rival Pokémon to face off against at those Gyms, so you’ll need to build up a stable of powerful Pokémon instead of relying on one heavy hitter to see you through.
You’ll also want to bear in mind the classic Pokémon strength/weakness matrix. For instance, water types are strong against fire, but weak against grass. Grass types, consequently, are weak against fire, and so on and so forth. Work this into your strategy as you build a well-balanced stable of Pokémon to knock an opposing team from a Gym.