There are a lot of classes in WoW that excel at PvP. Mages, however, are usually considered one of the best PvP suited classes. Many say that the only true way to PvP a mage would be a frost talent build. True, the frost tree is indeed excellent for crowd control and mana conservation, however, fire and arcane builds can also be effectively used if the right set-up is applied. Better gear will give your character more potency and playing battlegrounds and arenas will bring about better PvP specific gear. Although PvP specialised mages should have good gear - this is true of any class - a lot also depends on the player's skill and ability to react to the challenges faced.