Well, I feel I have to defend 6Teen. Yes, the show has plenty of stereotypes but I believe that, for the nature and premise of the show to work, these stereotypes need to be there. I mean, it's not like there aren't real teens that behave this way, the show just happen to be based on people like those.
The thing about 6Teen is that it really focuses more on humor and character development than in most of the issues it deals with. The characters are actually quite endearing once you get to know them as they're really the meat of the show. But you need to get past the stereotypes. If you can't do that, then 6Teen is not the show for you. Simple as that.
But how exactly is 6Teen a ripoff of Friends? I can see that both shows have a main cast of three guys and three girls, but how does that qualify as ripping off? It's like saying Ed, Edd & Eddy is a rip off of Peanuts because both series feature kids and animals with no adults in sight.