Sho owns a Pichu as part of his goal to have possession of one Pokémon each from the Pikachu evolutionary line. In Pikachu's Island Adventure, two Pichu, six Wynaut, and a Buizel were forced off their island by Meowth and his cronies, who then claimed it for themselves. In Lucario and the Mystery of Mew, Mew transformed into a Pichu during the Aura Guardian Festival tournament.

Pichu may be a combination of ピカピカ pikapika (onomatopoeia for sparkling), チューチュー chūchū (onomatopoeia for the squeak of a mouse), and possibly プチ puchi (petite), as well as being a contraction of Pikachu. It is female-only and has three spikes on the tip of its ear, but otherwise looks the same as any other Pichu.In Pokémon Adventures, Yellow was the one who gave Pichu its species name, creating it as a combination of the name of Pibu's parents, Pika and Chuchu. Check the Bulbagarden home page for up-to-date Pokémon news and discuss it on the forums or in the Bulbagarden Discord server.

However, Pichu are unskilled at controlling their electricity, and sometimes release it by accident when surprised, or when laughing, and shock themselves. Pichu charges itself with electricity more easily on days with thunderclouds or when the air is very dry. When Pichu plays with others, it may short out electricity with another Pichu, creating a shower of sparks. In All About Arceus IX, a Spiky-eared Pichu accompanied Pibu on gathering herbs for Celebi to cure Giovanni's disease.

Soon thereafter, Gold's own talent as the "hatcher" allowed a powerful Pichu to hatch, with which he was able to defeat the villain and free Celebi from the GS Ball using Raikou's massive electrical power.