I'm sure they can do uber trist, but it would take a very long time, usually you have a bunch of monsters on you at any given moment, and since zeal attacks adjacent targets, your not going to always hit meph/diablo/baal which means your not going to do very much damage or if any at all. Imo Smiters are the big cheese for doing ubers, of course many other builds can do it as well, such as a summon necro, and a conc barb with alot of ar and lifetap, but all in all the smiter is the most efficent ubering character in the game, able to walk in and out of uber trist with a torch in his paws in under 3 minutes.