Lag is mainly because the game is Peer to Peer type connection. That means it depends on the host of the game (The team leader). If your team leader is in the same region as you, you won't be getting any lag, if they are in some countries far away, you will get lag due to to a large ping session. 

The same when you are the team leader and hosting the game, if your connection is fast enough, your team member won't be getting much lag, but if your connection is slow, everyone in your team will be lagging except you.

So it's best to join a guild with people in the same region and play with them for lagless team battle experience.