This might be kicking a dead horse but here goes.
4 players with CD would be required.
Secure Tournament Mode would be used.
I would create a senerio that the 4 players would pair off and complete.
The 2 winners of that would play each other for the championship. With a different scenario.
If we manage to scrape together the 4 needed players,they will decide the theatre,etc of the battle I create.
The championship battle would be themed the same,but would be a larger battle.