Spiky-eared Pichu first appears in Pokémon HeartGold and SoulSilver as an event Pokémon obtained in Ilex Forest. She will appear and join the player's party if the Pikachu-colored Pichu (or one of its evolutions) is brought to the shrine as the first Pokémon in the party. She has her own unique in-battle and overworld sprites and cannot evolve or be traded outside of HeartGold and SoulSilver. Aside from her unique sprite, moves, and inability to be traded or evolve, she is nearly identical to a normal Pichu in that her base stats are the same as a normal Pichu's. However, her maximum stats for the Pokéathlon are different. If a Pokémon uses Transform on her, it will have a spiky ear.
Shiny sprites for Spiky-eared Pichu exist in the coding of the games, although it is impossible to obtain one due to the game assigning the Spiky-eared Pichu a fixed personality value that is predetermined according to the Trainer ID number and secret ID. This ensures that the personality value will never result in a Shiny nor a male Spiky-eared Pichu.
If taken to Professor Elm, it is revealed that she has traveled through time with Celebi. Elm claims that he and Professor Oak were researching the time travel abilities of Celebi, and claims that this Pichu proves his main theory. He adds that the reason she cannot evolve is because she has been time traveling for so long. He then calls all the Pokémon Center attendants to prevent Spiky-eared Pichu from being used in trades; however, the attendants do not permit her into a trading facility prior to this either. Spiky-eared Pichu is also unable to be transferred through the Poké Transfer into a Generation V game due to her past time traveling.
Spiky-eared Pichu's inability to be traded can be explained as being preventative of trading any alternate form to a game in which the form does not appear, as happens in Platinum, HeartGold, and SoulSilver when entering the trade center with Rotom in an appliance, Giratina in its Origin Forme, or Shaymin in its Sky Forme, by returning them to the forms they appeared in Diamond and Pearl. As Spiky-eared Pichu cannot freely change between forms, this explains the need to make her untradeable within Generation IV.
In the anime, Spiky-eared Pichu was shown to be a helpful Pokémon, which can be seen when it freed Cyndaquil by using Iron Tail on the collar that was used to control it. In the ending dedicated to it, however, it was shown to be competitive, as evident when it raced the Shiny Pichu up a tree and lost, and when it had an eating contest with the Shiny Pichu to see who could eat the most Grepa Berries and won. In that ending theme, it was also shown to be very sensitive, as it was seen crying when it got lost.
Spiky-eared Pichu first appears in All About Arceus IX, where it is seen accompanying Gold's Pibu as they help Celebi find the herbs needed to cure Giovanni's disease. When several Team Rocket Grunts try to stop Ken, Al, and Harry from helping Celebi under Giovanni's orders, they accidentally trample over the Pichu duo, which causes them to retaliate by shocking the Grunts with a combined Electric attack. When they meet up with Gold, Gold sees Spiky-eared Pichu and teases Pibu about finding a date.
In the Arceus and the Jewel of Life manga
In the manga adaptation of the movie, Spiky-eared Pichu is a wild Pokémon who the characters meet in the distant past. It assists the characters in escaping from the movie's main antagonist, Marcus.
Spiky-eared Pichu Cards listed with a blue background are only legal to use in the current Expanded format. Cards listed with a silver background are legal to use in both the current Standard and Expanded formats.
A picture of a Pikachu short poster that featured Spiky-eared Pichu alongside Pikachu and Piplup was leaked several days before this Pokémon was officially revealed.
It was first mentioned at the end of a movie preview of Arceus and the Jewel of Life when movie director Kunihiko Yuyama talked about a "small, yellow Electric-type that would save the world."
Spiky-eared Pichu's sprite in HeartGold and SoulSilver is in a different pose than that of a normal Pichu, but she retains the two frames that a normal Pichu uses in her animation; thus, she is the only Pokémon to have three animation frames in Generation IV.
According to Shōko Nakagawa's autobiography, the Spiky-eared Pichu was originally going to be a White Pichu (Japanese: ホワイトピチュー).
Spiky-eared Pichu appears as a Poké Doll plush toy.
Spiky-eared Pichu shares several similarities with Omega Ruby and Alpha Sapphire's Cosplay Pikachu. Both are female-only variants of the Pikachu evolution line who were introduced in remakes. They are both incapable of evolving, breeding, being traded, or being transferred to later games. They also both cannot be obtained Shiny, though Shiny variants exist in the game code for them. They are also both a palette swap in Super Smash Bros. Ultimate.
Spiky-eared Pichu is currently the only Pokémon without a 3D model in the core series games.
ギザみみピチュー Gizamimi Pichu
Literally "Notched-Ear Pichu".
From trois (three) and épi (cowlick).
From strubbelig (tousled) and Ohr (ear).
From spuntone (spike) and orecchio (ear).
Pichu de orelha cortada
Literally "Sliced-Ear Pichu".
Pichu de orelha talhada
Literally "Sliced-Ear Pichu".
From pico (spiky tip) and oreja (ear).
삐쭉귀 피츄 Ppijjukgwi Pichyu
Literally "Sharp-Ear Pichu".
刺刺耳皮丘 Cìcì'ěr Píqiū
Literally "Spiky-Ear Pichu".
For more information on this Pokémon's species, see Pichu.