The gladiators will likely be mongrelmen, grippli (if they can get into the city) and tasloi. They will likely be bunched in a way that 1 token represents 5-10 troopers and fight against baddies with tokens representing same. It would be similar to using the battle system rules. I don't think the party has stumbled upon a location where the baddie token represents that many yet. The baddies so far include: Yuan-Ti, Bullywugs, Bugbears, Gnolls, Deathwalker Cannibals, fire lizards and lizardmen.