Ninjask has been one of the best Baton Pass users since its introduction in ADV; this is largely because of its ability, which boosts its Speed for free every turn. Combined with access to Swords Dance, a base Speed that beats everything short of Deoxys-S, and an Attack stat quite usable by RU standards, it's clear why Ninjask is one of the most feared Pokemon at its role. Unfortunately, this very fact turns out to be one of its biggest weaknesses; when an opponent sees the ninja cicada in Team Preview, they know exactly what it will be doing and will almost certainly send out something that can hinder it. Ninjask's awful defenses alongside its 4x Stealth Rock weakness only exacerbate this problem, as Ninjask must take the lead position in most matches. Still, Ninjask can make or break games entirely through its passing ability.
This set is Ninjask's bread and butter: a basic passing set with the purpose of making a physical sweeper too strong for your opponent's team to handle. The combination of Substitute and Protect allows Ninjask to stall and let its ability do the work for it, buying turns to hopefully get a Swords Dance in as well. If Ninjask manages to pass both a Swords Dance and a Substitute, the game might as well be over. However, a Substitute + 3 attacks set is recommended for most receivers, as it is unlikely that Ninjask will be able to pass a Substitute intact, and the last thing any receiver wants is to be bogged down with status.
It is crucial to carefully decide which item to use to fit your team's needs. Leftovers is standard to allow for more Substitutes and generally extend Ninjask's longevity, but Focus Sash allows for the possibility of safely passing Swords Dance against something that could otherwise OHKO it. Mental Herb works as well, giving Ninjask freedom against an opponent's Taunt or Encore. Lum Berry is also an option, though Substitute will generally suffice for blocking status. X-Scissor is an option should Ninjask desperately need an attacking move, but this will greatly reduce Ninjask's defensive ability; use it at your own risk.Team Options & Additional Comments >>>
Ninjask is frequently seen as a Pokemon that does nothing but stall the opponent and has barely any firepower, which is precisely what makes this set so effective. Bug / Flying is a surprisingly effective type combination, resisted only by Aggron, Steelix, and Rotom among RU Pokemon, and the fact that Ninjask 4x resists two types and is immune to a third gives it plenty of opportunities to set up. As if this wasn't enough of a niche, Ninjask sets up while sweeping, allowing it to Baton Pass out to let an ally finish what it started, which is something most other sweepers would kill for.
The item choice is a very difficult one. Life Orb gives Ninjask several key KOs, but Focus Sash makes setting up much easier; if Ninjask hits +4, essentially only possible via Focus Sash, it might as well be GG. Other move options include Night Slash to hit Ghost-types or Substitute to scout and block status, but finding a spot for these moves is a difficult prospect.Team Options & Additional Comments >>>
While Ninjask has a good number of other options, few of them are viable, especially given how much Ninjask needs its four moveslots. One notable option is Roost. On paper, the move extends Ninjask's longevity, but in practice Ninjask needs every spare turn it can get to set up Swords Dance, and Ninjask is rarely able to pull off a Roost when it is not behind a Substitute. Toxic is another choice to surprise bulkier opponents attempting to haze or phaze Ninjask, but it does nothing to Steelix or Drapion and is seldom worth a precious moveslot. Hone Claws is an option over Swords Dance, but is only recommended if you intend to pass to Hustle Zweilous; Swords Dance is better in almost every other case. Dig can be used on the attacking set if you're terrified of Aggron, but this tends to lure in Flying-types, most of which resist X-Scissor. Lastly, Ninjask has access to Final Gambit, but it is completely outclassed at this role by Accelgor.
Checks and Counters
In general, when facing a Ninjask, it is extremely important to not give it time to set up—given free turns, Ninjask is all too happy to set up and pass to something that will sweep your entire team. Of course, it's not particularly fun to see a formerly slow sweeper suddenly become lightning fast just because Ninjask stalled you, even without the +2 Attack. If you want to prevent Ninjask from passing entirely, there are quite a few ways of going about this.
Ninjask despises facing priority attacks not named Mach Punch. Entei's ExtremeSpeed is extremely likely to ruin its day; even on the pure passer set with Protect, Ninjask is held to a simple +1 Speed pass. Likewise, Ninjask does not enjoy facing Prankster, as it is likely to be hit by a Thunder Wave before it can set up a Substitute. Anything with access to Roar or Whirlwind can bypass Ninjask's game. Munchlax is the most notable, as it avoids an OHKO from the attacking set, though it does take significant damage. While Ninjask hates Rock moves in general, Rock Blast and Stealth Rock really stand out. The former can OHKO even through Focus Sash or Substitute, while the latter makes it very difficult for Ninjask to come back in. Finally, Taunt and Encore can bypass Ninjask's substitutes to make its job very difficult, especially on the pure passer set, but this is a lesser option due to the possibility of Ninjask carrying a Mental Herb.