The FFIC uses a rotating pool of 19 different types of leagues in order to test the overall knowledge of participants. Selections from each tier are rotated in order to create maximum diversity between seasons and prevent participants from having to play in the same league types repeatedly. The league pool is broken into five tier groups according to factors such as player retention, required fees, and complexity levels. Each season 10 of the 19 leagues will be selected at random for players to participate in. Here's how those tier groups are broken out (click on a league name in the tables below for more details about that specific league)...
Long-Term Tier 
Each season participants will play in two leagues that focus on the strategy of player retention. These long-term league types will always make up two of the twelve leagues for the competition.
MFL Fee Tier 
To minimize how much money needs to be spent by members for the use of MyFantasyLeague, all league types that require settings only available on MFL have been grouped into a single tier. Only one of these will be used each year, which limits the annual fees to only $60. League types in this tier will be selected at random each year with no repeat from one year to the next.
Green Tier 
The Green Tier focuses in on league types that are the most common. While there are variations between these leagues, they are standard to most fantasy football players and in most cases, they are the least challenging of all the league types. Five of these leagues will be used annually. After the first year, two league types will be randomly selected to be retained while the other three are rotated out.
Yellow Tier 
Leagues in the Yellow Tier start to get a bit farther from the standard fantasy football leagues that most are familiar with. These leagues drastically alter one aspect of the game to create new challenges. Three of these leagues will be used annually. After the first year, one league type will be randomly selected to be retained while the other three are rotated out. A league type will not be retained two years in a row. The Survivor and Guillotine leagues will not be used simultaneously.
Red Tier 
The Red Tier is composed of leagues that are the farthest from a standard league type. These are leagues based around odd rule sets that can get out of hand quickly if everyone playing doesn't bring their A-game. Since these leagues can become unbalanced fast there will only be one used annually with no league type repeating from one year to the next.