warlock 2v2 and 3v3Follow

Hello....how bout that ride in?.....i guess thats why they call it Sin City

Ok so heres the scenario. My brother is a shaman, im a warlock, and my friend is rolling a new character. Would there be any class besides a mage that would suit a 3v3 team?
Also, the most suitable 3v3 team iv seen is (Resto Shaman, Frost Mage, and Destro Lock) Is there a build that uses shaman, lock, ????, where i can go affliciton instead of destro?

thank you