It evolves into Pikachu when leveled up with high friendship, which evolves into Raichu when exposed to a Thunder Stone. In Lucario and the Mystery of Mew, Mew transformed into a Pichu during the Aura Guardian Festival tournament.

In Celebi: The Voice of the Forest, a Pichu was seen in a window on a girl's shoulder during Ash's battle with Dundee. Pokémon HeartGold and SoulSilver: The Spiky-eared Pichu will appear at the Ilex Forest shrine if the player approaches it with the Pikachu-colored Pichu first in the party. Together with Magikarp, Rattata, Ninjask, Goldeen, and Seedot, Pichu is the easiest Pokémon to catch in Pokémon Ranger, with only one loop necessary.

Pichu made a cameo in Teddiursa's Picnic in a fantasy of Professor Elm's explanation about Pokémon Eggs to Gold. Pichu charges itself with electricity more easily on days with thunderclouds or when the air is very dry. In Magical Pokémon Journey, it is revealed in The Accidental Treasure that Pikachu and Clefairy had already met as baby Pokémon, Pichu and Cleffa. In the episode, Lyn's bag was accidentally taken by Bonnie, who had a similar bag with her Dedenne inside; they eventually got their bags and Pokémon back.

This is the only way to obtain Spiky-eared Pichu, and it cannot be traded, so only one can be obtained per game. It is female-only and has three spikes on the tip of its ear, but otherwise looks the same as any other Pichu. Gold, in his desperation, protected an Egg containing the offspring of Red's Pika and Yellow's Chuchu from the Masked Man. However, Pichu are unskilled at controlling their electricity, and sometimes release it by accident when surprised, or when laughing, and shock themselves.The Pikachu-colored Pichu was the first Pokémon to be given out over Nintendo Wi-Fi Connection outside of Japan. 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. Additionally, according to Junichi Masuda, Ken Sugimori came up with the idea for Pichu when Game Freak staff were trying to figure out a Pokémon to be the "next" Pikachu. Despite this Pokémon's cute appearance, those who want to live with one should prepare to be on the receiving end of its electric jolts. In Charging After Electrike, multiple Pichu were among the Electric-type Pokémon that charged the Prism Tower during a blackout.

Also, in The Miraculous Color of the Sky ~Best Friends~, Sandy and her Raichu are reincarnated as a little girl and a Pichu. When Pichu plays with others, it may short out electricity with another Pichu, creating a shower of sparks. Check the Bulbagarden home page for up-to-date Pokémon news and discuss it on the forums or in the Bulbagarden Discord server. 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.It is usually found in groups and often touch tails with other Pichu as a show of courage, creating a shower of sparks that can make them cry. The design of one of the brothers is similar to that of Ash's Pikachu and Sparky, in that it has a scruff of fur on its ear. She helped Pikachu and Piplup find the keys for the jail cell that held Ash, Dawn, Brock, and Damos. 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. In All About Arceus IX, a Spiky-eared Pichu accompanied Pibu on gathering herbs for Celebi to cure Giovanni's disease.

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.Sho owns a Pichu as part of his goal to have possession of one Pokémon each from the Pikachu evolutionary line.