Okay, I'm posting this so we can hopefully figure out what Nintendo and GF were smoking when they came up with this thing's Hidden Ability. Seriously, Zen Mode is the reason Darmanitan Z is the sole inhabitant of the Limbo Tier. It can only enter Zen Mode at half of its HP, and if it ever goes even one hit point up afterwards, it goes back to its regular form. And anything that can lower its health to that extent is going to take it out next turn, higher defenses or no higher defenses.
Seriously, why the hell would they create something as useless as that? You're better off going with Sheer Force, since it's actually usable in competitive gaming.
Seriously, why the hell would they create something as useless as that? You're better off going with Sheer Force, since it's actually usable in competitive gaming.