What Niley said. My druid is my main, and is about on level with naxx 25/uld 10, but the rest of my toons are basically just wearing heroic/badge gear, and they still have quite a few slots filled with blues. It's mostly about figuring out how to do a fight as opposed to having problems with gear I think. Having Niley's tank outgear the place certainly helps, but I feel that we could do the same with my paladin tanking, and all of his gear is straight from heroics/badges and even the AH.

As for grobbulus himself: Once we figured out that you barely have to move him (since we have no melee that have to get out of his dropped poison clouds) and you can just sit your guys in one place the entire fight and just run injected ones out and back, it was just about getting our timing with injections down (basically when someone got injected I would just face them towards a far wall and hit autorun. When it exploded, I'd run them back and repeat with the next injected). Where you see him dead is the entirety of where we moved him. Maybe 30 yards from his ramp.