Pokémon Insurgence has an online mode which allows you to battle and trade with other users, and to visit their Secret Bases. You can access trading and battling from your Pokégear. The first time you access the online mode you will have to register, and the next times you will only have to login. When you try to battle or trade using the online mode you should not switch out from the Insurgence window.
After you select the option you want to do, the game will request the username of the person you want to connect with. That person must write your username at the same time. If everything went fine, a connection will be established and you will be able to start. Because of this required synchronization, the Pokémon Insurgence Chat is a useful tool to establish trades, and also a great place to find fellow battlers and traders.
You can visit Secret Bases by entering a cave placed in your own Friend Safari. The game will ask you to register or login, and afterwards it will ask you the username of the person you want to visit. In this case the owner of the base does not have to do anything. You can also upload your Secret Base, which will allow others to visit it.
I can't connect to the online server! I can't access Friend Safaries!
The server sometimes experiences issues. Check the right part of this page to see the server status. If it is marked as online, check if someone else has made a recent post in the subreddit about the problem, or if it has been reported at the chat. Otherwise message either /u/Deukhoofd to restart the server.
Battling online does not work! I'm getting a marshal error when battling!
Battling when one of the participants has more than 4 Pokémon will produce an error. This is a known issue that is being worked upon. Meanwhile, limit combats to 4 Pokémon.
Shiny Pokémon appear as normal ones in the trading window, what is wrong?
This is another known issue. Please take extra care when choosing people to trade shiny Pokémon with, in order to avoid scamming. It is also a good idea to verify the Pokémon before trading by requesting screenshot links.