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.

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.