Pikachu serves as Ash Ketchum's primary Pokémon companion throughout the film. Traveling alongside Ash, Dawn, and Brock toward Crown City, Pikachu detects cries of distress within a nighttime forest and alerts Ash to Zorua under attack by Vigoroth. This intervention results in the group rescuing Zorua and pledging to help find its lost companion.

Later in Crown City, Pikachu follows Zorua's search for Zoroark. Accompanied by Dawn's Piplup, the three Pokémon befriend Celebi when it appears unexpectedly amid the city's escalating crisis. Pikachu participates in aiding Celebi after antagonist Grings Kodai harms it.

Pikachu remains present during the climactic confrontation at the stadium, where Zoroark exposes Kodai's deception through illusion. Following the resolution, Pikachu witnesses Zorua and Zoroark departing for their home region.