I like all of them. Especially that last one, what we could do is everybody could use [i]all[/i] of their characters in a large PM involving all the members, then we all battle it out xD

And the Tag-Team sounds fun, maybe my two characters could team up... 

The only idea I have is a bit of a full-out survival free-for-all, where there is no teams, but the fighters are put on a large course, filled with traps, baddies, and other creatures, and they'd have to either work together to survive the things or would kill eachother and win