A Class is a Champion type. There are six Classes in total, and every Class has an advantage over another (called a "Class Bonus") and a disadvantage to another. Every Champion has a minimum and a maximum of one Class, though they may technically be another (e.g. Scarlet Witch is a Mutant, as she is the daughter of Magneto, but she is Mystic in-game). While there are six playable classes, a seventh class, Combined, which has a Class Bonus against all other classes, does exist. However, it is exclusive to three Unplayable champions and one Temporary champion (Summoned Symbioid)
List of Classes
Cosmic Champions are characters that are alien or can be found in space. Cosmic Champions have a Class Bonus against Tech Champions, but are weak to Mystic Champions.