They could create a neutral "4th" class and pre-made loadouts for a "MLG" matchmaking gamemode, like in Halo 3 for people to practice with the "4th" class and pre-made loadouts; and for people to get a sense of how MLG functions, examples being learning callouts, map control and overall teamwork. Among other obvious things like dedicated servers, private matches, and actual weapon balance. Not to mention the special and heavy ammo would need severe reworking, and like in inferno there should be no radar.