Back on previous server I used to GM there were events called Pokemon battles. This would require two GMs on at once and a large enough room for the battle to move around the room. Players would vote on two MvPs (or normal monsters) to fight each other. Then the GMs would each summon one and the players got to vote on which one would win. The GMs would @duel eachother so the MvPs fought each other and saw who would win. Note not always does the obvious one win. I once saw ktul vs ifrit and believe it or not ifrit won. This continues until there is a top three (or whatever the GM chooses) and they receive top prizes. It is very fun to watch since its not the GMs choice but rather the players choice on battles which makes it more enjoyable to see this. If you can make it so there are two rooms to see each other but can't walk to either one so players who lose can stay to watch and get a prize for being there but wont sneak back in to try and vote.
Tl;dr - GMs summon monsters you vote for and they battle to the death!