Ninjask is a small, cicada-like Pokémon with two pairs of wings. Its body is mostly black with accents of yellow and gray. Most of its head is yellow, but there is a solid band of black between its gleaming red eyes. The band expands into a circular pattern on its forehead, between two pointed crests on the sides of its head. The underside of its head is gray and segmented, making it somewhat resemble a veil. On its back is a patch of black with a stretch of yellow, shaped like an upside-down letter Y. Most of its carapace and abdomen is black, but there is a ring of yellow near the tip. Its gray insectoid arms extend from its chest and usually have their small, yellow claws turned inward. There is a similar pair of back legs. It has large, veined wings with triangular, red tipping.
Ninjask is a very fast Pokémon that is said to be able to evade any attack and was long believed to be invisible due to its high speed. If it is not trained properly, it will refuse to obey its Trainer and cry loudly. Due to this, it is said to put the Trainer's abilities to the test. Hearing its loud cries for too long induces a headache. It lives in tropical and temperate forests, where it congregates around tree sap to feed.
Two Ninjask debuted in The Princess and the Togepi and A Togepi Mirage, under the ownership of Colonel Hansen. Along with a Shedinja, they were his main Pokémon.
In From the Cradle to Save, Evian used a Ninjask as his partner-in-training. It was first used to search for Angela's Kecleon after she assigned Ash and his friends to search for it. Later, it was captured by Team Rocket, but was freed by Ash's Grovyle.
In Pace - The Final Frontier!, Brandon used a Ninjask during his battle against Ash at the Battle Pyramid. Ninjask battled Squirtle but was eventually defeated.
In Zoroark: Master of Illusions, Goone used multiple Ninjask for various tasks, such as capturing and transporting Pokémon to attacking larger Pokémon en masse.
In a flashback in Glory Blaze!, Paul was revealed to have caught a Ninjask at some point during his journey. In A Real Rival Rouser!, Paul used Ninjask during his Full Battle against Ash in the Lily of the Valley Conference. Ninjask faced off against Gliscor before Gliscor was recalled and Infernape was sent out in its place. It eventually lost to Infernape.
In That's Just Swellow, a Trainer's Ninjask competed in the Crossgate PokéRinger.
A Ninjask appeared in the opening sequence of Destiny Deoxys.
A Ninjask appeared in a visualization in Hi Ho Silver Wind!.
In Saved by the Beldum, a Trainer's Ninjask was at the Ever Grande Conference.
A Coordinator's Ninjask appeared in Harley Rides Again.
In Following A Maiden's Voyage!, a Ninjask had been caught in the web of an Ariados.
A Ninjask appeared in Arceus and the Jewel of Life.
Multiple Ninjask appeared in Diancie and the Cocoon of Destruction, under the ownership of Riot. Two of them were used to carry Riot when he was about to steal Diancie.
In A Relay in the Sky!, a Trainer's Ninjask participated in the Pokémon Sky Relay. It was in a team also consisting of Vibrava and Shedinja.
A Ninjask appeared in Volcanion and the Mechanical Marvel.
Multiple Ninjask appeared in Lulled to La-La Land!.
A Ninjask appeared in Secrets of the Jungle.
Multiple Ninjask appeared in The Spectral Express!, evolving from a group of Nincada. One of them left behind a Shedinja, which entered one of Goh's empty Poké Balls and became his Pokémon.
||Ninjask, the Ninja Pokémon. Ninjask is said to be so fast it's able to evade any attack.
||Ninjask, the Ninja Pokémon, and the evolved form of Nincada. Because of its swift flying velocity, it can become impossible to see.
In The Cavern, a wild Ninjask flew away from a storm that a Primal Kyogre was creating.
In The Scoop, a Ninjask was working at TV Mauville.
Ninjask appears to be based on an adult cicada, with its colors resembling a bush cicada. As its species name implies, it may also be based on a ninja due to its name, quick movement, and natural ability to learn Double Team by leveling up (a common ninja technique in Japanese media) and various cutting attacks. This combination may be further inspired by stories of ninjas using cicadas to mask their own sounds, or a reference to the utsusemi no jutsu (cicada skin technique), a technique using decoys to misdirect opponents.
Ninjask may be a combination of ninja and mask.
Tekkanin may be a combination of 鉄火 tekka (gunfire), 忍者 ninja, and possibly 鉄仮面 Tekkamen (Man in the Iron Mask).