The default multiplayer modes, ofcourse. As well as the custom battle and ctf gamemodes(LRS, pest, roast tag, flag run, domination, jailbreak etc.). Race should be in there, too, since nobody plays it anymore. If there was a way to start the race with /cstart (is there? cause i don't know ). I really don't know what to do about the coop mode, since you can't be the best jj2 playing country if you didn't compete in ALL of the gamemodes.
Also, since the booty treasure contest is over, we should have maps for a treasure tourney
If only there was a team treasure hunt mode, that would be awesome