Planning to do challange mode golds with friends, what class should we bring as a 5th

[Senen]

they suck on pulling (hard to make easy aoe pulling without ninja over by dps)

Lolwhut?
You have Mocking Banner up for every pull that actually matters.

But yeah, I agree we deal less damage. For the survival part, I'm not sure, we may be slightly weaker than other tank class but it doesn't feel that noticeable.

[Shyzhi]

You need a strong ranged DPS, mostly hunter, Warlock or Ele sham like people have said. A warrior tank wont be bad to heal if they know how to play there class. Its better then a war DPS :P when i did my golds with friends our war DPS spent more time afk then attacking as most instances are so melee unfriendly lol