http://www.ign.com/wikis/call-of-duty-black-ops-2/League_Play
League Play is a new matchmaking system in Call of Duty Black Ops II. This system will allow players to play against people around the world on their own skill level. Instead of waiting for friends to get online, creating clans, or playing against unbalanced skill levels, people can play on a leveled field every time.

When starting League Play, the player will play in a series of five placement matches. After the matches, each player will be placed into one of the following skill divisions (descending order):

Masters
Platinum
Gold
Silver
Bronze
Iron

All Weapons, Attachments, Equipment, and Scorestreaks will be available in Create A Class. Set up the perfect classes without having to reach level 55 first. Since everything is available (except Camo), weapons will not increase in level. Rank Levels will only increase by 1000 if a match is won and 500 if a match is lost. Winning or losing a match will also affect a player's rank in their division.