Pachirisu is one of the new Pokémon appearing in Pokémon Diamond and Pearl. Little is known about it so far. It has a new attack called Discharge and knows Thunderbolt. Its abilities are Pick Up or Run Away.
The name Pachirisu is a portmanteau of the Japanese words "pachipachi", an onomatopoeia for electric crackling, and "risu", meaning squirrel.
Pachirisu appear to be small squirrels. 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. 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.
In the video games
Pachirisu can have either of two pre-existing abilities: Run Away, an ability that increases the chances of the player to run from battle; or Pick Up, an ability that allows the Pokémon to randomly find items. It is known that Pachirisu can use the new attack Discharge, an electrical attack that hits both of the user's opponents and its partner, similar to Earthquake and Surf (of which Surf has changed in the Fourth Generation of Pokémon.) It can also learn Super Fang by leveling up, which, prior to the 4th Generation, was unique to Rattata and Raticate. Its statistics are below average, with only mediocre defensive and speed stats and extremely poor offensive stats. Super Fang is it's only move that can cause considerable damage to higher-level enemies, as it automatically reduces their HP by half if it hits. Pachirisu is also one of 11 Pokémon dubbed "cute" and are thus allowed entrance into Amity Square, an area where Trainers can take walks with their allowed Pokémon.
In the pokemon manga
Lucas catches a Pachirisu named Pariu prior to the first chapter, "Pachirisu's discharge!". This Pachirisu is very independent and doesn't listen to anyone. It causes massive mayhem in a battle against Roark.However by the third chapter it listens to Lucas, but is still hyperactive and wild.
In the Pokémon anime
Dawn catches a Pachirisu in the episode "Twice Smitten, Once Shy". This Pachirisu is extremely hyperactive and seems to have a very naughty nature, as it delights in tormenting Ash and Dawn's other Pokémon. When Dawn tries to train it, it usually tries to run away. It was released because of the mayhem and recaptured by Dawn. In the episode "Pikachu's Caretaking!" Pachirisu had a dream to fly, so it attached some balloons to itself which later popped. This caused the ship they were on to move and fall into a waterfall because of all the Discharge.It is voiced by Chinami Nishurma