I guess the commonality I have is Structure. Someone or group is organizing the fight and running things. There may be real emotions behind the fight, but it allows for a wide variety of locations, rules, and the like. Sometimes, the opponents are forced to fight, other times, it's their idea and the 'host' just runs the venue.
Half my time speculating and preparing is just "how do people sign up for it/how does the villain gather women to fight?" logistics.