

Swellow initially struggled but with the help of Vladimir and his Pidgeotto, Ash was able to teach Swellow the move in Lessons in Lilycove. After this victory, Ash became determined to teach his Swellow Aerial Ace, beginning in Pokéblock, Stock, and Berry. It then struck with Wing Attack and knocked out Winona's Swellow, winning the battle for Ash. However, Ash quickly recovered from Hyper Beam and ordered Swellow to create a dust cloud to blind and slow Winona's Swellow down. Several episodes later, in Sky High Gym Battle, Swellow fought Winona's Shiny Swellow despite Winona's using more powerful attacks such as Hyper Beam and Aerial Ace. It then singlehandedly sent the sore losers Team Rocket blasting off. Desperate, it evolved into Swellow and easily broke through, using Wing Attack to flick the ring onto the goal and win the tournament, earning Ash honorary citizenship of Crossgate Town. Determined to win, Taillow flew into the storm, but was too small against the gale. In the final, Taillow went up against James and Dustox, starting strongly until a sand tornado kicked up. Unbelievable determination allowed Taillow to shrug off Electric-type attacks that defending champion Volt's Volbeat was using and it made a counterattack to fly to victory.

In That's Just Swellow, Ash entered Taillow in the Crossgate PokéRinger competition.

May then arrived at what Drew called the best part, Roselia used Solar Beam, and due to the paralysis Taillow was unable to dodge, causing the Solar Beam to hit Taillow and knock it out. Taillow attempted to dodge by flying upwards but it was hit by the Stun Spore anyways, paralyzing it. It then went for a Peck but Roselia used Stun Spore.

Taillow swiftly dodged it and Roselia used Petal Dance, which Taillow dodged by flying upwards. Taillow used Peck which hit Roselia, whom quickly counterattacked with Magical Leaf. In Pros and Con Artists, Ash used Taillow to battle Drew and his Roselia, as shown in a flashback later in the episode Ash was sure Taillow could beat Roselia due to Taillow having a type advantage. Taillow's impressive flying techniques allowed it to match Nicholai's newly caught Pokémon well. Its first official battle was against Nicholai and his Zigzagoon in In the Knicker of Time!. Ash then sent it out and Brock helped it recover. On Brock's advice, Ash captured Taillow to prevent it from getting hurt anymore. Taillow then showed up alone and challenged Pikachu, and even though it took countless Thunderbolts and a Thunder from Pikachu it still kept fighting. It also led the entire flock on a ceaseless attack until Brock and his Forretress intervened and used Explosion to drive them away. It stole Max's chocolate and challenged Pikachu to a battle. It was the leader of a flock of wild Taillow. Ash caught Swellow as a Taillow in You Never Can Taillow.
