Pichu, the Tiny Mouse Pokémon. A pre-evolved form of Pikachu. Despite their size, Pichu release bursts of electricity that can shock even humans. However, Pichu are unskilled at controlling their electricity, and sometimes release it by accident when surprised, or when laughing and shock themselves.
– Ash’s Pokedex
Pichu is the first baby Pokemon in National Dex order. Of course they’d make a baby version of the popular Pikachu.
Pichu is featured a lot in the anime, despite not belonging to any of the main characters. First there’s the Pichu brothers, 2 reoccurring Pichus who show up in many of the pre-movie Pikachu shorts. In the Arceus and the Jewel of Life movie, a spiky-eared Pichu was introduced, who saved helped Pikachu and Ash escape from their prison and save the world. This spiky-eared Pichu became an event Pokemon in HGSS. It even has its own custom sprite. It’s always female, cannot evolve, and cannot be traded out of HGSS (probably because the custom sprite data isn’t in any other game). You’d need to get a Pikachu-coloured Pichu from a wi-fi event, then go to the Ilex Forest to find the spiky-eared Pichu and catch it. It’s pretty much a gimmicky event Pokemon.
Probably due to its popularity, Pichu is a playable character in Smash Bros Melee. But it seemed to be an inferior version of Pikachu (since it hurts itself with electric attacks). In Brawl, Pichu was taken out of the playable roster and downgraded into a trophy.
Stat-wise, being a baby Pokemon, it has pretty low stats and isn’t that useful in battle. It has decent Speed, but very low Defense and HP.