Greninja is a bipedal, frog-like Pokémon. It is mostly dark blue with a yellow chest, a white triangular marking over each eye, a light blue four-pointed star on each thigh, and yellow on the lower half of its face. It has red eyes with white pupils and its mouth is hidden behind a large, pink tongue that wraps around its neck and extends outward behind its head. Running down the middle of its head is a fin-like extension, and there is a similar fin on each side of its head. Light blue webbing connects its head fins. There is a large, white bubble-like bump on each elbow and knee. Its back feet have two toes, while its front feet have three toes. Each digit has a bulbous tip and yellow webbing.
Greninja moves with the speed and grace of a ninja. It uses swift movements to confuse its enemies while it slices them up with weapons made of compressed water, most commonly in the form of throwing stars. These throwing stars are sharp enough to split metal. In the past, Water Shuriken and Mat Block were its signature moves.
Through a transformation called Bond Phenomenon, Ash's Greninja in the anime and any Greninja with the Ability Battle Bond in Generation VII can change into an alternate form called Ash-Greninja. In this form, Greninja's skin turns a lighter shade of blue, while its face gains red stripes and its cheeks and side fins turn black, changing shape to resemble Ash's hair. Its legs are stronger in this form, and it gains the ability to form large Water Shurikens on its back.
Greninja, the Ninja Pokémon, and the final evolved form of Froakie. Greninja can compress water into sharp-edged throwing stars. With the grace of a ninja, it slips in and out of sight to attack from the shadows.
A Greninja briefly appeared in GOTCHA!, under the ownership of Serena.
Five Greninja appeared in Detective Pikachu. They were genetically modified and put in chambers. They were later used to chase after Harry Goodman, and also Tim and Lucy when they broke into Howard's facility.
This Pokémon was unavailable prior to Generation VI.
Greninja's overall appearance is based on a frog, and it may have been inspired by horned frogs from the generaMegophrys and Ceratophrys due to the spiked protrusions above its eyes. Its color scheme and body shape is similar to that of the splendid leaf frog. The bubble-like protrusions on its body may be based on a toad's parotoid glands, possibly referencing the traditional myth of toads causing warts, though they may also be remnants of Froakie and Frogadier's frubbles.
As its species name implies, Greninja is also based on a ninja. Japanese culture associates frogs and toads with ninjas based on the folk story "The Tale of the Gallant Jiraiya" (児雷也豪傑物語 Jiraiya Gōketsu Monogatari) about a ninja who can shapeshift into a large toad. Greninja and its pre-evolutions may also draw inspiration from the thief or rogue class as they often rely on speed and stealth and are often seen as nimble or ranged combatants while tending to focus more on dodging attacks rather than withstanding damage.
Greninja is a combination of grenouille (French for frog) and ninja.
Gekkouga is a combination of げこっ geko (croak) and 甲賀流 Kōga-ryū. It may also derive from 月光 gekkō (moonlight), in reference to a popular conception of ninja running through the night or to Greninja's Dark typing, or a combination of both.