Cure and Second Wind is a must for a smooth experience. Protect also is good to have to lessen the damage.
I think a Duo can be done by any class combo as long as you have the above skills. If it's a DoW/DoM combo just make the DoW take the damage.
GLA - A Tank
MRD- Can be a Tank
PUG- Good at evading...possible tank/offtank?
DoM also can wipe through mobs rather quickly with their damage. The only issue I see with them are running out of MP and the constant down times at lower levels(from my experiences of getting my CNJ to 15).