After playing shaman for 2 years...all i can say is (I PVP MORE KEEP IN MIND)

Resto. can survive againest rogues - making rogues complaning. And can do decent healing.

Elemental keep your distance and you'll do fine, try to kill ur enemies as fast as you can. ( Seen some as engineers and made things to stun their enemies u might want to consider this to keep ur distance. )

Enchancement get good equipment and you'll do fine. Other then this play and learn.

Learn to play them....

My experince with other classes

Warriors can't heal themselves...... Only bandages can heal u while fighting if u can spare the time in a fight. No healer and we have a problem.

Rogues are cheap and easy to learn but PVE your not in demand. Learn to hide and run before u die. We can kill shamans without getting hurt sometimes (ele, enchance only)

I don't believe all classes should be balance to each other when it comes to pvp but i do believe one class should be the weakness of another.