Well, Garr is the only boss that has been solo'd so far, due to many bosses needing several key things to work.

MC has been done a few times by a group of five on my server tho, they're set up is this.

Prot paladin
resto druid
disc/holy priest
frost mage
combat rogue

This is why this set up would work in all fights in mc.

Mage/druid = decursing
Paladin/priest = dispelling
priest = fearward (magmadar)
Rogue = sustainable dps over looooong fights
Two healers = in good gear, endless healing capabilities.
Druid = res in case somehting goes wrong. (oops)

You really need decurses and dispellers tho. And some form of sustainable dps (hunter could work as well), whilest probably not essential, would make it all a whole lot nicer.

Also, should get tier5+ quality gear too, in my opinion. :P In your set up, whilest you could rely on decursing with felpuppies. (olol). I wouldn't want to rely on it, get a mage or a druid MINIMAL one preferable one of both tbh. :P