Probably the most unnecessary evolution of DPP, Dusknoir is about as good as Dusclops was in the previous generation. The extra Attack helps it in a few places, such as in countering Gyarados by using ThunderPunch, but Dusknoir sorely misses good STAB. Generally, it is relegated to Dusclops's old duties, namely spinblocking, spreading burn with Will-O-Wisp, and countering a few specific sweepers. However, Spiritomb and Rotom-A give it significant competition for the role of a spinblocker, and it generally loses to Rotom-H.
While Dusknoir faces serious competition for the role of spinblocker from Rotom-A, it is more than capable of functioning as an effective spinblocker on its own merits. It boasts some significant advantages over the electronic appliance, most notably better defenses. There are three effective Rapid Spin users in the OU metagame: Starmie, Forretress, and Tentacruel. The latter two have no hope of breaking through Dusknoir's impressive defenses; it is only Starmie that needs special consideration. Starmie doesn't threaten Dusknoir much unless it is carrying Choice Specs, as Dusknoir can otherwise hit Starmie with ThunderPunch or STAB Shadow Sneak, both of which are super effective, or leech Starmie's HP whilst replenishing its own with Pain Split.
Dusknoir also makes a handy counter to many physical attackers, as it can either burn them with Will-O-Wisp or take them down with the appropriate attack. In particular, Will-O-Wisp cripples common Pursuit users, such as Tyranitar and Metagross. Pain Split is a rather poor method of healing, but it's all Dusknoir has outside of the very risky Rest. Nevertheless, Dusknoir can use its ridiculously low HP and Speed to its advantage by taking hits from high HP opponents and sapping their health while recovering its own.
Earthquake is one of Dusknoir's strongest attacks and provides good coverage overall. Specifically, it easily deals with Heatran, who would otherwise happily switch in on Will-O-Wisp and Fire Punch for a Flash Fire boost, and also 2HKOes Infernape. Ice Punch helps with Dragon-types such as Dragonite and Flygon, and has great type coverage alongside Earthquake; the combination of Earthquake and Ice Punch is resisted only by Bronzong in OU. Alternatively, Fire Punch takes out Weavile and prevents Heracross from utilizing Guts to sponge Will-O-Wisp and eliminating Dusknoir with Pursuit. It hits Steel-types—especially Scizor and Forretress—super effectively as well, but note that it will neither OHKO the former nor 2HKO the latter. ThunderPunch, as previously mentioned, 2HKOes Gyarados.Team Options & Additional Comments >>>
Trick Room sets Dusknoir apart from other Ghost-types. Dusknoir is an excellent Trick Room supporter, as it is both slow and extraordinarily bulky. The strategy is straightforward enough: switch in on something that poses little threat to Dusknoir, such as bulky Fighting-types and most defensive Pokemon, set up Trick Room, then switch out to a slow sweeper that can take advantage of the three remaining turns of Trick Room.
Will-O-Wisp is a great move to have on a Trick Room team, as it not only weakens defensive Pokemon so that your sweepers can break through them, but also cripples threatening attackers, most notably Tyranitar, who is an extremely common switch-in to Dusknoir. In Trick Room, Dusknoir can always use Will-O-Wisp before Tyranitar can use Crunch. Pain Split provides Dusknoir with some instant, albeit unreliable, recovery, and if Dusknoir chooses its Pain Split targets carefully, it should be able to stick around for quite a while and set up Trick Room multiple times. Earthquake and Shadow Punch are both solid attacking moves, and the latter in particular hits Heatran that might come in to steal a Flash Fire boost from Will-O-Wisp.Team Options & Additional Comments >>>
Gravity is Dusknoir's biggest niche move. Not only is it the only Ghost-type Pokemon and one of the very few Pokemon overall that have access to the move, Dusknoir can also use it well, especially if given Spikes and Toxic Spikes support. DynamicPunch is Dusknoir's main attacking move. Under Gravity, it has 82% accuracy, and therefore an 82% chance to cause confusion in addition to a solid 100 Base Power. The confusion works well with Will-O-Wisp, which has 100% accuracy in Gravity, as a turn of confusion damage means another turn of burn damage, even if burn does halve confusion damage. However, Earthquake is an option over DynamicPunch as it hits every single Pokemon under Gravity, and it has double the PP of DynamicPunch. Pain Split is the recommended last move as it helps keep Dusknoir alive, but Shadow Sneak remains an option to finish off weakened Pokemon and hit frail Psychic- and Ghost-types for decent damage. Shadow Sneak also has perfect type coverage alongside DynamicPunch.Team Options & Additional Comments >>>
Once again, this is a set that sets Dusknoir apart from its bulky Ghost brethren. This set uses Dusknoir's immunities to easily switch in and set up a Substitute, and then deal large damage to Dusknoir's usual counters from Dusknoir's often-underestimated Attack stat and its impressive physical movepool. In particular, Focus Punch outright OHKOes Tyranitar, a common switch-in to Dusknoir.
The choice between Sucker Punch and Shadow Sneak is difficult. Despite the lack of STAB on Sucker Punch, it is still more powerful than STAB Shadow Sneak, and Sucker Punch's greater power allows Dusknoir to OHKO the likes of Gengar and Alakazam. However, Sucker Punch will fail if your opponent chooses not to attack Dusknoir, and it has a maximum of 8 PP. The choice between Fire Punch and Ice Punch, on the other hand, depends on who you want Dusknoir to beat: Heracross or Dragonite. As Heracross almost will never hesitate to switch in, Substitute + Fire Punch can be used to severely cripple it. Substitute will force the frequently Choice-locked Heracross to reveal its hand, and Fire Punch will OHKO it after a bit of residual damage.Team Options & Additional Comments >>>
Dusknoir's movepool and respectable base Attack stat make it a viable user of Choice Band. Although slow, Dusknoir packs quite a punch and has the ability to counter many Pokemon depending on its choice of moves. Focus Punch lands an easy OHKO on Tyranitar, Weavile, and Heatran, and is Dusknoir's strongest attack, but requires good prediction. Shadow Sneak gives Dusknoir a STAB priority move with which to OHKO Gengar, Azelf, and Alakazam. Alternatively, Sucker Punch has good synergy with Focus Punch and makes your opponent struggle to decide whether or not he should attack. However, Sucker Punch's usage is very situational and could easily backfire, especially considering its meager 8 PP.
The last two moves should depend on how you want Dusknoir to function. The elemental punches will all hit specific targets depending on your needs: Fire Punch Heracross, Forretress, and Scizor; Ice Punch Dragon-types and Gliscor; and ThunderPunch Gyarados and bulky Waters. Trick is an interesting option that Dusknoir can use to cripple some of its counters, most notably Spiritomb. Most of Dusknoir's counters aren't physical attackers and hence don't fear Will-O-Wisp, and many will not enjoy the burden of the Choice Band. Trick also forces switches, which might allow Dusknoir to fire off a free Focus Punch. However, it is worth noting that Dusknoir's power will be reduced after it Tricks its Choice Band onto an opposing Pokemon. Do not feel that Dusknoir has to use Trick, though; another elemental punch can viably go in the last slot.Team Options & Additional Comments >>>
Dusknoir can use a Rest + Sleep Talk combo to good effect, but Rotom-A boasts better typing, movepool, and stats for such a set. Toxic can take the place of Will-O-Wisp on any of the sets, but Toxic can be used on almost any defensive Pokemon, and Dusknoir desperately needs Will-O-Wisp to keep opposing physical attackers at bay. Calm Mind is usable, but Spiritomb is more suited for this job thanks to its typing and higher Special Attack. Counter can surprise powerful physical attackers, such as Heracross looking to 2HKO Dusknoir. Just don't overuse it, as Dusknoir isn't an ideal user of the move with its pitiful HP.
Checks and Counters
Dusknoir might be able to cripple them with Will-O-Wisp or a super effective attack, but if they get in unscratched, Dusknoir has real trouble with Pursuit users, namely Tyranitar, Weavile, and Heracross. As Dusknoir is often without Brick Break or Focus Punch, Tyranitar can usually switch in more safely than the others. Heracross, however, can get a Guts boost from Will-O-Wisp and do some serious damage. Houndoom's Pursuit is a lot less threatening due to its lower Attack stat, but it can absorb Fire attacks and hammer Dusknoir with either Dark Pulse or a Flash Fire-boosted attack.
Heatran is a significant problem for Dusknoir that lack Earthquake or Focus Punch, as it can come in on any other attack and deal high damage with its Fire attacks, especially if it gets a Flash Fire boost. Spiritomb won't take much damage from any of Dusknoir's attacks and can easily beat it with Dark Pulse. Taunt + Dragon Dance Gyarados can set up on Dusknoir that lack ThunderPunch. In fact, most Taunt users can cause problems if they aren't weak to Dusknoir's attacks. Finally, Toxic and Will-O-Wisp will greatly hinder Dusknoir's tanking capabilities if it doesn't have Rest.