Depends on what game you play, deathmatch is fastest but harder when Peeps with Storm Hammer joins the fight, Team Battle is not that fast but easier since there some people are on your side, Point capture is fun just hope that your team actually works together, Flag capture is same as point capture, Deadly games is soo fun! But soo hard! Also soo slow! Reason is obvious.
Fastest way to get Exps and coins imo is..
1. Get a second device.
2. Make a 2 player deathmatch match.
3. Set timer to 7 min
4. Now make both devices join the same match.
5. Keep killing the person on the second device from your main device
6. ???
7. Profit!
Note. Dont set any password.
have fun