Every character was a stereotype? Have you even watched the movie? The way the characters develop and come together as a group to challenge the roles
How did they challenge their roles? At the end of the movie they explicitly say that they can't be friends in every day life, but only as a convenience on weekends. Their actions are
still guided by how other people will perceive them.
They haven't changed one bit.
Each of their starting roles was as a stereotype.
*The nerd needs good grades because it is expected of him.
*The jock needs to play sports because his dad wants him to play or something to that effect.
*The criminal is a criminal because he is abused, which is a stereotype because movies never like to assume that the person is schizophrenic, bipolar, has thyroid problems, etc; let's just stick to the abuse stereotype because it's the easiest to understand and it makes people sympathize with that character.
*The bitchy white chick is a stereotype suburbanite from the upper-middle class who doesn't get a lot of attention from her highly successful parents.
*The quiet girl is lonely and craves human interaction. She lies about being a nympho to get a response, then she says she's a liar to get a response, she dumps her purse to get a response, and she's voluntarily there at detention just because she's lonely. She's a different version of the geek stereotype. Some geeks are very loud and talk about geeky things with their geeky friends while some geeks are socially awkward and don't have many friends. This girl is the geek with no friends stereotype.
So then all of the stereotypes start talking. omg you're a stereotype? Me too! We're so alike! The movie concludes with the sentiment that different stereotypes face different problems. For example, Italian plumbers need to fight clogged pipes but Mexican car mechanics put whistle tips on car exhaust systems while black people describe how those whistles sound. Apparently the whistles go woooooooooo. Oh and the low self esteem suburbanite chick rebels against her parents by making out with the criminal that is nothing like her father. This is so original, not like any stereotype we've seen before.