Pikarla_Boss is an alternately colored Pikachu that lives in the Pikachu Valley in the Alola Region. It has always had a crush on
Pikala's Pikachu ♀ (Curly) and when it saw that
Ash Ketchum's
Ash's Pikachu was becoming friendly with
Pikala's Pikachu ♀ (Curly), it got jealous. It's also possible that it didn't approve of an outsider.
It hit
Ash Ketchum's
Ash's Pikachu with electric shocks signalizing a duel which is one of the rules in the valley. Humans are not allowed to interfere in the battle and the first Pikachu to bite the other's tail wins.
Ash's Pikachu was a lot more experienced in battling and quickly won the duel with an Electroweb.
When Rocket Gang attacked,
Pikala's Pikachu ♀ (Curly) was captured by them but Pikarla_Boss used the Z-move Catastropika to on them and
Jessie's Mimikyu to send the Rocket's flying while releasing all the Pikachu at the same time. After being rescued by Pikarla_Boss,
Pikala's Pikachu ♀ (Curly) fell in love with him.