Pachirisu are small squirrel-like pokemon. These Pokémon have what one could call a "cute" appearance, due to their small size, overall appealing look, and obvious similarities to Pikachu, making it the "electric rodent" of the 4th generation of Pokémon, since it has so many similarities to Pikachu. Pachirisu's main body color is a white tinged with a very light pastel blue. Their heads are quite large and the bodies are small, giving Pachirisu a somewhat comical appearance. They have two yellow circles on their cheeks, which create and store electricity. Their ears are blue and pointy, with a small protrusion pointing down into its face from the base of the ear. Their paws are short and bear three fingers. Their tails are curly and are very large in proportion to their bodies and are capable of unleashing static electricity for use in battle or other tasks a Pachirisu may perform. In fact, they can store their charge in bits of fur and then release them off their bodies. They use these charged puffballs and store them with berries they hide, like squirrels do, to keep others from stealing them. Their tails also bear three spikes on the part where it begins to curl. A blue stripe starts at the forehead above the nose, and runs down the back all the way to the tail just past the three tail spikes.
The male Pachirisu's blue stripe extends slightly farther down its forehead than that of a female Pachirisu. A shiny Pachirisu has a pastel purple stripe instead of a blue one.