Naganadel first appeared as a Poipole in Ultra Origins!, where it accompanied the Ultra Recon Squad to Alola and met the group. It battled Lewis' Aipom briefly with no clear winner and later witnessed Aipom battle Tapu Koko. At the end of the episode, Poipole went through an Ultra Wormhole with the Squad.
It reappeared in A Beastly Encounter!, where it was attempting to help the Ultra Recon Squad calm a Blacephalon and a Stakataka. It later went with Soliera, Lewis, Lillie and Dulce to try and calm Blacephalon and stop it from meeting Stakataka. Despite its best efforts, the two Ultra Beasts encountered each other and began a huge battle in the Poni Grove.
In the following episode, Poipole was once again used to battle Blacephalon. This time, Poipole was better prepared for Blacephalon's tactics and was able to subdue the Fireworks Pokémon, allowing the Squad to send both Ultra Beasts back to their own worlds.
It later appeared with the Ultra Recon Squad in A Mission into Darkness! and accompanied the Squad, as well as Lewis and Lillie, to the Altar of the Sunne & Moone, where it witnessed Nebby and Lewis' Cosmoem evolve into Lunala and Solgaleo respectively. Poipole then travelled to Ultra Megalopolis with the group.
In A Towering Battle of Legend!, Poipole accompanied Lewis and Lillie to the top of Megalo Tower to face Ultra Necrozma. It teamed up with Lewis' Solgaleo and Aipom, as well as Nebby, to defeat Necrozma. It was severely injured by Necrozma's Photon Geyser, but with Lewis' encouragement, it was able to rise again. When Necrozma launched a Dragon Pulse, Poipole bravely countered it with its own newly-learnt Dragon Pulse, protecting the group and causing it to evolve into Naganadel. With its new-found power, Naganadel was able to fight on more even grounds with Necrozma, eventually defeating it with the help of the other Pokémon. After light was restored to Ultra Megalopolis, Naganadel returned to Alola with Lewis and Lillie and helped to protect Alola from the Ultra Beasts.
In The Calm After the Storm!, the Ultra Recon Squad prepared to return to Ultra Megalopolis. Phyco noticed that Lewis and Naganadel had forged a strong connection while battling Necrozma. He then requested that Lewis catch Naganadel and use it in the upcoming Alola League, so that Naganadel could experience more intense battles like the one it had with Necrozma. Lewis accepted Phyco's request and caught Naganadel using a Beast Ball given to him by Zossie.
As a Poipole, Naganadel was very happy and playful, quickly making friends with the group and their Pokémon. It appeared to be relatively inexperienced in battle, but was also shown to be quick to adapt to its opponent's strategies, as seen in its battles with Blacephalon and Necrozma.
After evolving, Naganadel retained its friendly traits, but became much more serious overall. Its battling skills also improved greatly, allowing it to fight Necrozma more evenly than before.