Boss Battle Style Contest
Audience are the bosses and player have to show us their moves by 'attacking' them to instead the audience's hp bar named as Excitement level. First group to fill up the bars win.
GM will inform players of the rules and ask them what type of contest they want to participate. Players can only use moves associate with the declared contest type in these contest.
Audience HP will be 300 hp/ per contestant that attacks it. So 1 boss vs 3 players would be 300 HP and 900 HP.
Boss naturally should have all his moves belongs to that contest's type. Player should still have the advantage with class feature and x-amount players actions.
For further complicated mechanic, certain effect changes the audience mood and affect the rate of their excitement level. Maybe half or double rate increase and some effect that reduce other side's hp. Fluff can play a role in achieving these effects, but should cost a turn since they are pretty strong effect.