Corki will be great in teamfights. He will poke the enemy team like hell. He can even let tryndamere do undying ragequit. When they are going inside a bush or out of sight use your Q to see them. when they get you try do get away with your barrier and flash and your W. For the rest just ult them so they get aced.

He can be very good to make the enemies scared. Just keep at the tower and ult untill they run. When it are 5 stand behind the turret so they cant poke you. You can might get some kills even you fighting against 5.

Its easy to get away from a gank. When it isnt a jumping champ just W. when its a jumping one first wait untill it jumps to you then W.

First poke alot with your Q and basic attacks. Later use your ult and he will be flaming like hell to you :D.