It's a free-for-all. The current Justice League in a massive fight, each member versus one another. While they are all against each other, they may make quick alliances to take down a stronger team member (e.g. Superman). Battle set in New York Times Square, no civilians but cars/buses/etc. for cover and whatnot. For the sake of fairness, Cyborg and Batman get 30 mins prep each, but cannot leave the area - they can only work out battle tactics/get into position/whatever.
Round 1: Win by incap, morals on.
Round 2: Win by kill ONLY, morals off (but no bloodlust).
Who shall be the last one standing?