oh gosh is that a little puff of steam right there in the official art oh wow that is adorable
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There's a running theme with these Gen 5 Pokemon: power creep has set in, and they are here to run a train on your shit. Darmanitan has Physical Attack for days, and decent speed to boot. Plus Sheer Force boosts attack power by 30%, so he hits like Hulk Hogan on fire.
But I also love his design. Giant flaming eyebrows? holy check, yes. And did you see his teeth? Darmanitan isn't any dumb herbivore, this boy is a straight-up carnivore. And what he eats is everything. See, it's based on a gorilla, but very loosely. The body retains that round shape of Darumaka, and it just looks like a natural evolution.
Now, I suppose I ought to talk about Zen Mode.
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I'm not really sure what to think about this one. If Darmanitan has its hidden ability, when it goes under 50% health, it goes into Zen Mode. In this mode, it trades Attack for Sp. Attack, and loses its speed in exchange for pretty good defense. Also, gains a Psychic sub-type.
This is a strange sort of idea, and doesn't work very well in practice. You see, no matter how many beefy Sp. Attack moves you load it up with, you won't get to use them. It triggers at the end of the turn you lose more than half of your health, and on that next turn, you'll move too slow to do anything. That added defense doesn't help, because your health will be so slow.
If he could just switch forms whenever he wanted, with a unique move or something, that would be usable. But as it is, regular Sheer Force Darmanitan is just too damn good to waste time mucking about with Zen Mode.
So in the end, Darmanitan is absolutely great. Zen Mode is lame. But fortunately, it's completely optional, so no harm no foul. Still kicks ass.
Overall: 10/10