Ah, Darmanitan. Never been a fan of it's design, an opinion I admittedly have for many 5th gen pokemon, but eh. Quick rundown:
Abilities:
Sheer Force - Darmanitan's only standard ability, but it's a fantastic one: Sacrifice any and all secondary effects from your attacks in exchange for a 30% power boost. You all know it, you all love it. Darmanitan can make pretty good use of it, with it's flexible movepool and impressive offensive stats.
Zen Mode (Hidden Ability) - The signature ability required to unlock the Zen Mode form, Darmanitan gets a boost of 60 points to its base stat total and adopts a much more defensive statline. This sounds all fine and dandy, until you realize that it only activates and
remains active while Darmanitan is <50% of its total HP. Since the standard form (which would need to tank the hits) has tish defensive stats, it's extremely likely the slower Zen Mode form will get shot off the field in the following turn before it can do anything, assuming it even
survived that first hit.. Compared to Sheer Force, this is a hard pass.
Regular Darmanitan -
Stat Strengths:
- 105 Base HP gives Darmanitan a modest amount of health-based bulk, but that's about all that can be said for it there.
- 140 Base Attack hits like a van speeding through a school zone. With the combo of Sheer Force, which can be easily stacked with a Life Orb, this can let Darmanitan hit really, really hard.
- 95 Base Speed is respectably quick, especially if invested in. It's certainly not breaking any records, and comes up a bit short compared to many faster options, but it's certainly workable.
Stat Weaknesses:
- 55 Base Defense and Special Defense is genuinely awful. Combined with Darmanitan's poor defensive typing, this basically negates its otherwise great HP values.
- 30 Base Special Attack is trash, short and simple. Not that you'd be running a special-set Darmanitan, given it's impressive physical stats and movepool.
Zen Mode Darmanitan-
Stat Strengths:
- 105 Base HP is pretty key, as it's the only thing that'll let you activate Zen Mode in the first place. Unfortunately, it won't be a stat you can really capitalize on compared to its other defenses.
- 140 Base Special Attack lets Zen Mode Darmanitan capitalize on the relatively diverse special movepool it has access to with impressive results. This is slightly complimented by the dual Fire/Psychic typing it receives while in Zen Mode.
- 105 Base Defense and Special Defense, combined with its HP stat, would be excellent for a bulky pokemon. Unfortunately, Darmanitan needs to be at half health or less in order to remain in Zen Mode, so these stats are far less effective than they'd otherwise seem.
Stat Weaknesses:
- 30 Base Attack is half the price of activating Zen Mode. While you'd probably be running an exclusively special toolkit on Zen Mode builds, this makes the viability of a mixed set relatively nonexistent. Even Belly Drum won't really make it workable, especially in light of the next problem.
- 55 Base Speed is terrible. It's now far too slow to run for a standard sweeper sort of build, yet it's too fast to out-slow most pokemon who'd benefit from Trick Room. This means that Darmanitan is extremely likely to take an additional hit before it gets any opportunity to utilize Zen Mode to any real degree. Certain support builds (like Speed Boost Baton Passers) can kind of make up for this, but why would you bother supporting Darmanitan for that when so many other superior options exist?
Recommended Attacks:
Flare Blitz - Absurdly powerful, especially if under the influence of Sheer Force and a Life Orb. Even pokemon who resist it will be left reeling.
Fire Punch/Fang - Strong STAB moves primarily due to Sheer Force boosting their effectiveness. The drop off in strength compared to Flare Blitz is very noticeable, but the lack of recoil damage will greatly improve your Darmanitan's lifespan.
Superpower - Another impressively powerful attack, Superpower gives Darmanitan a solid coverage option thats consequences won't really mean anything to it; Darmanitan's defense is already bad enough and its attack stat is high enough that it can afford one or two drops before switching becomes necessary.
Zen Headbutt - A solid coverage move that gets the slight bump from Sheer Force.
Belly Drum - If you can afford to set up with this, Belly Drum will let you ruin the day of at least any one pokemon on your opponent's team. You may want to run such a set with a Sitrus Berry or Wish support if you want to get the most bang out of this buck.
U-Turn - A decent scouting move that lets Darmanitan keep up the momentum for the switch while at the least slapping some chip damage on the foe.
Earthquake - Your run-of-the-mill strong coverage move, extra handy for double battles as well (assuming you have a partner who flies/levitates). Works wonders, not much else to say about it.
Rock Slide - Just like Earthquake, Rock Slide is a solid coverage move, only with significantly less risk to your partner and benefiting from Sheer Force.
Recommended Natures and EV's:
Jolly, 252 Spe, 252 Ata, 4 Hp - This'll help get the most out of your Sweeper-style build, maximizing Darmanitan's speed while obviously wrecking shop with its already obscene attack stat. If you feel the speed won't be too much of an issue, you can opt in for an
Adamant nature instead, if you wish to absolutely top off your phsyical hits, though this likely won't be necessary.