The trash that spawns along with Pummelcrush can be pulled without agroing him, and you can clear a path to pull Pummelcrush without clearing the adds.
Pummelcrush hits up 5K, but has low attack. His minimum hit is around 1000. He has 700K Health and low regen, is partially slowable, and it is relatively easy to slow.
The AE is easily resistible, and the knockback can be countered using levitation.
Of the bosses in this event, Pummelcrush is the second easiest (Vegeroth being the easiest, Earthcrusher the hardest)