Two decades before the main events, Celebi encountered Grings Kodai in Crown City. As Celebi tried to escape through a Time Ripple, Kodai attacked, rendering it unconscious. Kodai touched the ripple, gaining future visions but reversing Crown City's time flow, devastating its greenery. Celebi vanished afterward.

Twenty years later, Celebi returned, unaware Kodai sought to recapture it to renew his fading powers. It greeted wild Pokémon and revived patches of vegetation, revealing its bond with forests. While restoring life, Celebi befriended Zorua, who searched for his captive mother, Zoroark. When hostile wild Pokémon threatened Zorua, Celebi intervened to calm them, showcasing its peacemaking nature. To comfort the distressed Zorua, Celebi grew grass resembling Zoroark's fur, demonstrating empathy.

Kodai captured Celebi, injuring it to force disclosure of the Time Ripple’s location. Too wounded to fly or flee, Celebi relied on Ash and companions for transport toward the ripple while evading Kodai. Celebi hid strategically in Ash’s backpack, while Zorua created an illusory decoy to misdirect Kodai—highlighting Celebi’s cooperative ingenuity despite vulnerability.

Upon reaching the Pokémon Baccer Stadium, the ripple’s true site, Celebi entered the energy field. This rejuvenated it, allowing Celebi to heal the dying Zoroark, repaying Zorua’s kindness. After Zoroark’s recovery and Kodai’s defeat, Celebi made Crown City’s greenery bloom anew, restoring natural balance. It departed through the ripple to resume time-traveling, with Zorua pledging eternal friendship.

Throughout, Celebi displayed a friendly, compassionate, and protective demeanor. It forged a deep bond with Zorua, shielding him from threats and soothing his distress. Beyond time travel, its powers encompassed healing, environmental revival, and pacifying agitated Pokémon, cementing its mythical role as guardian of forests and life. Its actions reversed Kodai’s ecological damage and reunited Zorua with Zoroark.