Ash first captured Swellow in "You Never Can Taillow!," when it was just a little Taillow. It had stolen Max's chocolate and engaged in a battle with Pikachu. Despite having a type-disadvantage against electric types, Taillow stubbornly continued to fight until it succumbed to its exhaustion and was captured.
Taillow first battled Nicholai's Zigzagoon in In the Knicker of Time!. Since it was its first major Pokémon battle with Ash, Taillow's skills matched with the opponent's as well. The battle's end was unknown. In You Said a Mouthful!, Taillow fought and lost to Anthony's Pelipper with a Magby inside used Flamethrower on it.
Taillow had its first Gym battle with Ash in Brave the Wave!, where it fought against Brawly's Machop. It landed powerful hits from Wing Attack, but was taken out by a devastating Cross Chop. In the rematch, he was switched out for Corphish.
In "Pros and Con Artists!," Taillow battled Drew's Roselia and managed to outmatch a powerful Petal Dance, but got paralyzed by Stun Spore after coming in too close and losing the match. It also lost to May's Torchic after exposure to Ember.
In "That's Just Swellow!," it was entered with Ash in the PokéRinger tournament. Using its determination and strong aerial skills, Taillow managed to get to the final round of the tournament. Taillow and Ash faced James with Jessie's Dustox. In the battle, they fought strongly until a sandstorm appeared. Taillow flew in the storm, but was immobilized in the process. With strong and persistent confidence, Taillow suddenly evolved into Swellow and broke free from the sandstorm with Wing Attack and flung the ring onto the goal and won.
After evolving during the Pokémon Ring Contest, Swellow has partaken in many of Ash's battles in Gyms and Leagues and has got a good amount of wins under its wing. In Sky High Gym Battle!, it participated in Ash's sixth Gym battle with Flying-typed Gym Leader Winona of Fortree City. It fought her Shiny Swellow, despite it having more powerful attacks including Hyper Beam. Ash's Swellow recovered after taking hits from Hyper Beam and created a dust cloud to blind her Swellow while slowing it down and taking it out with a Wing Attack, winning Ash's Feather Badge.
Swellow continued to become strong and determined like Ash. In "Solid as a Solrock," it teamed up with Pikachu in two double battles with Tate and Liza in the Mossdeep City Gym. The first battle was interrupted by Team Rocket. During the second battle, Swellow and Pikachu struggled against the two Gym Leaders' Pokémon. Swellow used its new technique, Double Team, to distract the two opponents while in the air. Pikachu then used Thunder in the clouds, which hit them both. By storing the electricity in their bodies, Swellow and Pikachu turned it into Thunder Armor, and Swellow used it take down Lunatone with a powerful Aerial Ace while Pikachu defeated Solrock with Iron Tail. Swellow was used to battle Juan in Eight Ain't Enough during his Gym battle at the Sootopolis Gym. It then strongly fought against his Wiscash, but got Tickled and hit by Hyper Beam. It then recovered and knocked it into the air using Aerial Ace. In the air, it dodges Hyper Beam and slams Whiscash with a powerful Quick Attack, sending Whiscash into the water. But before it did, Swellow knocked it out with Aerial Ace. Against Juan's final Pokémon, Milotic, struggled hard to fight off the -type by dodging Hydro Pump and struck with Aerial Ace. After using Double Team, Milotic used Twister to destroy the clones and hit Swellow, knocking it out.
Swellow was used in many Pokémon battles during the Ever Grande Conference in the Hoenn League. In two of these battles, the ones against Katie and Tyson, Swellow defeated two of its opponents in a row and when battling Morrison it fought his Gligar to a draw.
Swellow was one of the four Pokémon besides Pikachu that Ash took with him to challenge the Battle Frontier in the Kanto region. It teamed up with Corphish in "Tactics Threatics" where they fought against Dome Ace Tucker's Arcanine and Swampert. After a long battle, Swellow landed a powerful Aerial Ace on Swampert while Corphish used Crabhammer on Arcanine, defeating them both and ending the battle.
Swellow was used again in "Ka Boom With A View," where it fought Palace Maven Spenser who had his Venusaur defeat Ash's Heracross. After changing tactics from Ash, Swellow easily dodges Venusaur's Vine Whip and Razor Leaf attacks. At a beach, Swellow dodged all of Venusaur's attacks using a Double Team/Quick Attack combination. A powerful Aerial Ace finally defeats Venusaur. Swellow fought Claydol but was quickly defeated by Hyper Beam.
After journeying through the Battle Frontier, Swellow was left at Oak's Lab in Kanto when Ash left for his journey to Sinnoh. In The Semi-Final Frontier!, Swellow was used in the Sinnoh League battle against Tobias but was defeated by his Latios's Luster Purge without landing a single hit.
It is set to reappear along with all of Ash's Pokémon in an upcoming episode of Best Wishes Season 2.
|Peck||In the Knicker of Time!|
|Wing Attack||A Tail with a Twist|
|Quick Attack +||Brave the Wave|
|Aerial Ace +||Lessons in Lilycove|
|Double Team||Solid as a Solrock|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- Swellow was Ash's first Hoenn Pokémon to fully evolve.