There are several ways young one.
The way of the Grasser (snitch)Tell on them! About everything they do to you or anyone else, make their lives a living hell or simply make it slightly inconvieniant.
The way of the cronic liarSpread those romours about them, you know the ones I'm talking about
The way of the WarriorThe most simple and it worked for me when people tried to bully me in school... KICK ***!