Having uniforms would stop the teasing and discrimination about clothing, but there is more to tease or discriminate someone about rather than just clothing. Such as hygiene, looks, personality, intelligence, race, and the list goes on. So unless people somehow find a way to be perfect in everyone's opinion, teasing and discrimination won't stop.
As for violence, it's the same story. Uniforms would only stop the smallest percentage. In some ways uniforms actually make violence less preventable by eliminating one major warning sign. For example the black trench coats that were worn in by the murderers at Colorado's Columbine High School shooting. Of course I'm not saying we should arrest anyone who wears a trench coat, but the way that someone dresses can say a lot about their personality.
If you're thinking that uniforms will end symbols of being in a gang such as gang colors, think about how many other ways that a gang member could symbolize that they were in a gang such as rolling up your sleeve or leaving out the tag on your shirt.
Uniforms wouldn't help stop cliques. People have cliques because in a clique you have the same interests as each other, you can relate to each other, you get along with one another, etc. not because you shop at the same stores.
Wearing the same thing as someone else would hardly help the poverty issue. It doesn't change the fact that you are poor. It just masks the fact that you can't afford new clothes but there are other, less noticeable signs of poverty like never having lunch money, or at the high school level, your car could be a sign.
In my survey of Douglas High...