First off, there is not currently any way to battle friends per-say, or battle other Pokemon, at least not like in the old games. The only way to do this currently is to become level 5, and then find a gym near you that you can take control of.
You’ll find gyms all over the map but chances are you won’t be able to wander around your house to find one. From our experiences it seems like gyms tend to be around places where people tend to group around like parks, stores, etc. I believe this was done to have as many people around the gym as possible so that people have to ‘defend their turf’ in a sense. A captured gym will show up with a color (red, blue, or yellow) while an unclaimed gym will be gray. A Pokemon above a gym represents what Pokemon that trainer has defending the gym.
When you capture a gym you have to assign a Pokemon of yours to defend it. That Pokemon is subsequently removed from your current collection until it is defeated by another trainer visiting that gym. Simply winning 1 battle at a gym isn’t enough to take it over, each gym has a “prestige” level that must be whittled down in order to take it over.
How does combat work in Pokemon Go?
Unfortunately combat is a ton simpler in Pokemon Go then in the main games that everyone is used to. The battle is no longer turn-based, in fact it is virtually automatic and has to do with taking advantage of the elemental advantages of your Pokemon and making sure you have a more powerful Pokemon in the fight. Essentially you tap the screen to throw your Pokemon out there and tap to make your Pokemon attack. You can swipe left or right to help dodge attacks and also when your battle (blue bar) meter fills up you can press and hold on your Pokemon to make it use it’s special skill. We’ve included a video from a Youtube user that we found showing a battle below.
Throughout the battle your Pokemon are bound to take damage and as we have seen thus far there is no way to automatically heal or recover health over time. In order to heal up injured Pokemon you must use items like Potions and Revives which you can purchase at Pokestops.