It sort of depends on what's special about the special mob.

Something like a low level transmuter mob like the mobs in question are actually about the easiest thing for a poor tanking group to take on because, while they have offensive spells, their melee attacks are few and weak compared to all of the unspecial mobs of their level. Something like a pre-parry healer/shaman/druid might be a really good tank there since most of the damage that's coming out is unblockable anyway.