Although Ninjask's stats and typing scream mediocrity, it has all the right tools to establish a niche that has made it noteworthy in every generation since its release. However, the coming of the fifth generation heralded Ninjask's fall from grace. Its former OU home has finally caught up with Ninjask, leaving it to wield its Speed passing abilities in NU. Ninjask's blazing Speed stat, rare Speed Boost ability, and access to Swords Dance and Baton Pass make Ninjask the ultimate sweeping assistant and a necessity in Baton Pass teams. After just a few turns of idling, Ninjask can easily turn the tide of battle, and give its team a decisive advantage.
Unfortunately, Ninjask has terrible defenses which force it to resort to Substitute and Protect to keep it alive. Ninjask's typing also grants it numerous weaknesses, including a dreaded 4x weakness to Stealth Rock. To make matters worse, NU has few usable Rapid Spin users, so Ninjask will struggle to switch in more than twice in a game. However, Ninjask is still a threat to prepare for; its unchecked presence can lead to a sweep in just a couple of turns.
Ninjask is known for one set only. With its Speed Boost ability and access to Baton Pass, Ninjask can accumulate Speed boosts by just using Protect and Substitute. Baton Pass is the lynchpin of this set, and enables Ninjask to offload its boosts to any one of the slow yet powerful sweepers that reside in NU. Substitute is another move that Ninjask can potentially Baton Pass; it is also useful to keep Ninjask safe while it accumulates Speed boosts. Ninjask can easily set up a Substitute on Pokemon such as Tangela, Jumpluff, and Choice-locked Sawk. However, Ninjask's terrible defenses leave its Substitutes easily broken by unresisted moves, and if Ninjask is caught without a Substitute, it won't last long. Protect hoards more boosts while also letting Ninjask obtain more Leftovers recovery; when used in conjunction with Substitute, Ninjask can be extremely hard to take down. If you feel like playing Ninjask in a more offensive manner, Swords Dance can be used instead. If a physical sweeper safely receives both Speed boosts and a Swords Dance boost, the opponent will be hard-pressed to keep their team intact. X-Scissor is the only attacking move used on the set; it prevents Ninjask from being useless when Taunted and also lets it do respectable damage to targets such as Musharna.Team Options & Additional Comments >>>
Ninjask's often forgotten base 90 Attack can be utilized more effectively with a Choice Band. A set consisting of U-turn, Aerial Ace, X-Scissor, and Night Slash can not only break through common walls such as Tangela and Musharna, but also efficiently scout the opponents response to Ninjask. Unfortunately, Ninjask cannot touch Steel-types outside of the poor Dig; Pokemon such as Probopass and Lairon can thus wall Ninjask to no end. Choice Band Ninjask also finds it difficult to switch in repeatedly as Stealth Rock will end it after just three switch ins. Roost can increase Ninjask's longevity and counteract the effects of Stealth Rock; however, Ninjask is extremely frail and finds little time to use the move effectively. Although Ninjask's HP stat isn't amazing, it can still use Final Gambit which can take out frailer Pokemon such as Marowak if Ninjask is at full health; however, it comes at the cost of Ninjask's life and Ninjask often has better things to do. Hone Claws can be passed instead of Swords Dance if your designated recipient is either Zweilous or a Pokemon reliant on low accuracy moves such as Stone Edge.
Checks and Counters
The biggest counter to Ninjask, as already implied, is Stealth Rock. Just by switching into the dastardly hazards, Ninjask will lose 50% of its health. The lack of viable Rapid Spin users in NU compounds this weakness and ensures that Ninjask will only have a few attempts to successfully set up a sweeper before it succumbs to its arch-enemy. Bulky Rock-types such as Golem are prime switch-ins to Ninjask as they can set up Stealth Rock or squash the bug with a 4x super effective Rock Blast that hits through Substitute and Focus Sash.
As Ninjask relies a lot on Baton Pass and Substitute, phazing is a perfect way of rendering it useless. Not only does phazing strip Ninjask of all its boosts, it also forces Ninjask to take more Stealth Rock damage the next time it switches in. Phazers such as Bastiodon and Altaria can blow Ninjask away while taking pittance from X-Scissor. Taunt and Encore are equally disruptive as the former forces Ninjask to attack with its pathetic X-Scissor while the latter can lock it into a setup move. However, the speedy Ninjask can easily Baton Pass away before those moves take effect, and only Prankster users such as Murkrow will be able to stop it before it flees.
As many teams cannot reliably prevent Ninjask from passing Speed boosts, the best way to deal with it is to just hit the recipient hard. Pokemon such as Choice Band Rapidash Choice Specs Charizard are useful in this regard. All in all, if you can keep Stealth Rock on the field and hit the recipient hard, Ninjask should not be too much of a problem.