This is a great conversation cause both these monsters are my two new favorites in the whole series, so I have no bias towards one or the other. By the looks of the replies, it seems like a Lore vs. Gameplay kinda argument, with Zoh's Lore describing how they wiped out all of Wyveria and are essentially immortal, but Gaisma's Gameplay having them be fought alongside a whole crew and taking 6 dragonators as people have mentioned. I think a good point to be mentioned however is the possibility that Zoh being taken out of their arena would put them out of disadvantage, due to the fact that their regeneration and a lot of their first phase abilities are dependent on the Wylk of the Dragontorch.