The players start off in the hub world, in which they can practice or play around with their skills. Then they can move over to the arena to start the first boss fight.
There are multiple stages to the boss fight. Naturally with the progressing stage the boss will become more agressive, stronger and faster, hence the fight is going to eventually become harder. To move on to the next stage, the players have to either damage the boss up to a specific threshold or they have to a combined attack or some specific cooperative action. Optionally there is also the possibility to unlock a secret tip. At last the players have to perform a "coop-finisher" in order to finish off the boss.