Hikari captured this Pachirisu during her travels in the Sinnoh region. Its hyperactive and disobedient nature led to temporary release, but Hikari intervened to protect it from Team Rocket and successfully recaptured it when it voluntarily returned.

Early on, it frequently discharged electricity uncontrollably, disheveling Hikari's hair. It displayed a notable fondness for poffins, similar to Munchlax's affinity for Pokéblocks, and once threw a tantrum over a destroyed one. Despite energetic and occasionally mischievous behavior, it gradually became more responsive to Hikari's commands.

Pachirisu played a significant role in Hikari's contest career, participating in the Floaroma Town Contest appeals stage and contributing to her Hearthome City Contest victory alongside Piplup. It once fell ill storing excessive electricity but recovered quickly after defeating Team Rocket. After Ursula's Gabite stepped on a poffin, Pachirisu learned Super Fang, a move crucial for winning Hikari her fourth ribbon by defeating that same Gabite in a contest battle.

Alongside Buneary, Pachirisu helped create the "Ice Chandelier" combination technique by merging Discharge with Ice Beam, a strategy recommended by Thomas. This technique proved effective during the Grand Festival against Ursula's Gabite and Flareon, securing a comeback victory despite type disadvantages.

Later, Pachirisu traveled with Hikari to the Unova region, interacting with Ash's Oshawott by kicking away its scalchop. It appeared briefly in the Journeys series and was featured in the movie *Arceus and the Jewel of Life*, participating in the background during Hikari's activities at a lake near the ruined temple.

Throughout Hikari's journey, Pachirisu evolved from an initially challenging partner into a reliable contest companion, showcasing strategic battle contributions and consistent loyalty.