So yeah, there are three styles for Jake, metro/prep/ and DB....hahaha XD.
but yes, I think if Jake tried hard enough he could have been a prep, but he just didn't care enough. I could see him as the quiet strong type that girls have a secret crush on. but his association with marco, who fits in more with the laid back/slacker/jokers group probably has Jake leaning more toward just being that normal average guy who happens to possess very good qualities.
As for Tobias, I think he could actually go skater look and style if he wanted to.
Cassie...by association with Rachel could be prep, but i think if she cared she could probably do better than Rachel! She's a thinker, so not only prep, but smart and deadly intelligent, so she could take a lead. if she wanted to. otherwise, i think cassie might actually fit in with the goodie goodie slightly nerdish slightly odd girls.