Major appearances
Pichu Brothers
Pichu in the anime
A Pichu Egg in the anime

The Pichu Brothers are a pair of Pichu who have appeared in several places, including 皮卡丘 & Pichu, Camp Pikachu, several episodes of 神奇宝贝 Chronicles, and the 神奇宝贝 Channel special Pichu Bros. in Party Panic. Their 设计 is similar to Ash's 皮卡丘 and Sparky, in that one has a scruff of 毛皮 while the other does not.
Spiky-eared Pichu

A Pichu with a spiked ear, known as Spiky-eared Pichu, appeared in Arceus and the Jewel of Life. She helped 皮卡丘 and Piplup find the keys for the jail cell that held Ash,...

Pichu- Pichu, the Tiny 老鼠, 鼠标 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 由 accident when surprised, 或者 when laughing and shock themselves.

In the manga
Gold's Pichu in 神奇宝贝 金牌 and Silver: The Golden Boys
In the Magical 神奇宝贝 Journey manga

In Magical 神奇宝贝 Journey, it is revealed in The Accidental Treasure that 皮卡丘 and Clefairy met as baby Pokémon, Pichu and Cleffa.

Also, in The Miraculous Color of the Sky ~Best...

Trivia

Pichu used to be game director Junichi Masuda's 最喜爱的 Pokémon.[1] His new 最喜爱的 is Victini.[2]
Pichu is the first baby 神奇宝贝 in the National Pokédex listing.
Pichu is the first 神奇宝贝 in the National Pokédex to be a pre-evolution of a 神奇宝贝 from a 前一个 generation.
Pichu is the first 神奇宝贝 in the National Pokédex to have 更多 than one form.
Pichu is the only Generation II 神奇宝贝 to be playable in Super Smash Bros. Melee (although many others have appeared from Poké Balls). Like in the anime, it hurts itself when using electrical attacks.
Pichu is the only Pokémon...

Physiology

Pichu is a small ground-dwelling rodent. Its 毛皮 is very short, and it is pale yellow in color. The tips of its large ears are black, and it has additional black markings on its neck and tail. Its tail is short, but still bears some resemblance to the large lightning-bolt structure it will develop later on in life. It has pouches in its cheeks, which are pinkish colored and used for storing electricity. Its nose is extremely small, almost like a dot. It is classified as a quadruped, but many have been known to walk easily on their hind legs.
Gender differences

Pichu normally have no...