Probably, girl vs girl combats are generally not good for corruption. Someone has to be a male and "punish" his opponent to make things spicy enough.
As a corruption fan, what can I say... That's a wrong takeaway. Just, no.
The first two replies nail it, read them again, please. Corruption is about mental changes. And the problem with your proposed scenario is not that it's FvF combat or FvF adversity and not FvM. There are great corruption games with both fem corruptor and fem corruptee.
What doesn't work in your scenario is that you don't have an apparent corruptor. You have these girls competing, all of them pure, including the (fem)protag. Further complicating the matter, the proposed scenario doesn't offer the corruptee any carrots. So who's going to corrupt who, and for what reason? They lose the fight
and get molested? Why on earth would they even consider losing?
Okay, here's your FvF combat, but with a few corrupting incentives woven in:
1. Girls fight, winner gets money, loser can buy her way back into the tournament.
2. Buyback can be done with money (from prev winnings) or by
allowing to be molested by the winner.
3. The winner gets her
winning pot multiplied depending on the degree of depravity she inflicts on the loser.
4. (Optional rule) A contestant can earn a handicap by doing something lewd during the fight, like fighting topless, or willingly taking aphrodisiac, etc.
These 4 fairly simple rules create powerful incentives for a cast of pure girls to slowly corrupt themselves, no "male punisher" needed, at all.