I just realized a few things about the tournament.
Almost everyone whose "gimmick" we understand, is now allied to the Strawhats. With a few exceptions, those people were mostly in blocks B and C, which got the most attention so far. The reason we didn't get to see much of block D, is that a large number of the contestants therein will end up as opponents for the bock B and C allies of the Strawhats. The ones from block C that aren't established as allies to the Strawhats? Jean Ango is a sniper who throws weapons, in a non-arena style fight, he'd be much more dangerous. Kelly Funk is able to take over anyone's body with his power and specifically calls out wild beasts as acceptable targets, when he appears as an enemy, he'll have taken over one of the animals in Doflamingo's kingdom. Bobby probably won't end up fighting due to his timid nature. From block D we have four other people who we never really saw fight or don't even have an idea of their style.
Rolling Logan, Meadows, Damask, Mummy, Jean Ango and Kelly Funk (probably using the fighting lion as a host body), will be opposed to Luffy and his tenuous alliance, letting the Colosseum fighters show off a bit more than before, and maybe give us explanations on some of their gimmicks.
Cool theory. Maybe Burgess or Bellamy would be leading them.