Pikachu serves as Ash Ketchum's primary Pokémon companion throughout the film. It is present when Volcanion crashes near the group's campsite and instantly springs into action when Volcanion shows hostility, positioning itself protectively near Ash. During the journey to the Azoth Kingdom and Nebel Plateau, Pikachu remains steadfastly at Ash's side, engaging in skirmishes against opposing forces. It confronts Team Rocket when they attempt to intercept the group under Alva's orders.

In confrontations with Alva's mega-evolved Pokémon army, Pikachu demonstrates strategic battle capabilities. It coordinates attacks with Ash's Greninja and other team members, unleashing Electric-type moves like Thunderbolt against multiple opponents simultaneously. During one battle sequence, Pikachu employs Razor Wind, a move unseen since its earlier evolutionary stage as Fletchinder. At the climax, Pikachu joins the assault on Alva's flying fortress, contributing directly to disabling the weapon systems and protecting Nebel Plateau from destruction.

Following the conflict's resolution, Pikachu witnesses Volcanion's apparent sacrifice and subsequent survival. It receives recognition from Volcanion as an honorary member of Nebel Plateau alongside Ash's other Pokémon, acknowledging their cooperation during the crisis. Pikachu then remains with Ash as they return to the Azoth Kingdom and continue their journey.