So, do that. Don't make characters fit into roles. Envision people as how you do that.
For example, say you have the Six Student Clique
. Model them all off how actual students are and how would they relate to each other to work out that way. One may be the sweet innocent cute girl but maybe she has a fondness for say soccer. Another one in it might be the jock. Knows everything about sports, could care less about school much. Naturally this makes those two have common ground.
Delving further a third one has an interest in journalism covering everything from news to sports and more, additionally he's friends with the jock. Fourth could be the casual basketball player with a knack for cracking jokes. Fifth is the Genki Girl
cheerleader. (Go figure...) Sixth is the brains of the outfit, not so much skilled at sports or well-connected but he fits in by being the brains everyone can turn to for help in a tight spot.
There you go, six different characters not complete set into six archetypical roles. Some overlap but each could stand on their own if expanded upon right. Alternatively, it gives you countless relationships/team-ups for countless plot possibilities.