As a wild Pokémon
Ambipom was first seen as an Aipom in Slaking Kong!, worshiping a giant Slaking with several other mountain-dwelling Pokémon. She also stole Ash's hat, much like Ash's Primeape did 428 episodes earlier, with a group of Aipom getting food to offer the Slaking. Later, Aipom joined the other Aipom, as well as several Mankey, Vigoroth and Slaking, to attack the giant Slaking, which turned out to be a mechanical robot made by Team Rocket. She then helped in returning the stolen berries to Taylor. Later, after Ash and his friends left Taylor's home, the group sees Ash's hat on a rock. After wondering who placed it there, they found out that it was Aipom, due to an apple and a flower she left with the hat. The group then continues their journey as Ash says Aipom is a cool Pokémon after all. Unknown to them, the happy Aipom was watching them from a nearby tree.
Aipom soon reappeared in the next episode, May, We Harley Drew'd Ya!, stealing the hats of the participants before making off with Ash's hat again.
In Thinning the Hoard, due to her causing too much trouble, Ash attempted to catch her. After Pikachu used Quick Attack to get Ash's hat back and Thunderbolt to weaken her more, she was still able to foil Ash's capture attempt.
In Channeling the Battle Zone, as well as the previous episode, after watching May in the Kanto Grand Festival, Aipom became thrilled with battling and challenged Ash and his Pikachu for a battle; as he won, Ash finally captured her in front of a huge crowd.
In Aipom and Circumstance!, Aipom became jealous of Pikachu's closeness to Ash. Aipom also seems to have a certain penchant for headgear; aside from taking Ash's and other participants' hats, Aipom wore a daisy chain on her head and put on a ceremonial crown that the locals had trouble getting off. The members of a crowd who wanted to crown, as well as Ash and his friends, attempted to remove the crown from her head so she would not become their king for a year. With the help of a Belue Berry's sourness, the crown was finally taken off. Ash then hugged Aipom and told her not to get into trouble all the time. As Ash laughed a bit when he told her this, Aipom blushed.
Aipom's gender was confirmed in the Japanese version of the said episode while Aipom was nearby gathering flowers. May said, 「エイパムやっぱり女の子ね？」 Aipom is a girl after all, isn't she?. In DP048, Dawn also explicitly calls Aipom a girl, and in the dub of Steamboat Willies!, both Aipom and Buneary are referred to as girls when Dawn saw them wearing dresses and excitedly exclaimed "Buneary and Aipom you girls look so cute!", confirming them to be female.
Aipom enjoys participating in Pokémon Contests, but is also eager to battle. Her interest was first perked in Thinning the Hoard! where she took an interest in May's battle with Harley. Aipom also watched her battle with Drew before enticing Ash into catching her. While Ash had Aipom, she usually sat on his left shoulder when outside of her Poké Ball, in contrast to Pikachu sitting on his right shoulder.
In order to bring back Torkoal to battle Brandon's Registeel in Overjoyed!, Ash sent Aipom to Professor Oak, where Aipom had trouble adjusting to the new environment and Ash's absence, even attacking the Professor. However, after Ash's second defeat, Aipom returned.
When Ash left for Sinnoh, he wanted to leave all of his Pokémon but Pikachu behind as he did when leaving for Hoenn. However, Aipom snuck aboard the boat he was traveling on to accompany him on his new journey. Aipom proved to be necessary as a backup; as soon as they arrived, Team Rocket kidnapped Pikachu, and Aipom helped find them. During her journey through Sinnoh, Aipom defeated Paul's Chimchar in battle and helped Ash capture his Starly.
In Mounting a Coordinator Assault!, Aipom entered her first Contest with Ash. They got through the Appeals Round but lost the first Battle Round to Zoey and her Glameow. After the battle, Zoey suggested that Ash should let Dawn raise Aipom.
In A Gruff Act to Follow!, Aipom put up a fight against Roark's Cranidos in Ash's first Gym match in Sinnoh, but lost.
In their rematch in O'er the Rampardos we Watched!, she went up against Roark's Geodude. Geodude managed to avoid a lot of damage from Aipom while countering with its attacks, but Aipom was able to connect a super effective Focus Punch and defeat Geodude. Aipom next went up against Rampardos. Aipom uses Swift, but it doesn't affect Rampardos at all. Rampardos uses Headbutt, but before Aipom could dodge it, it is hit and knocks out.
In Borrowing on Bad Faith!, Aipom entered an unofficial Contest under Jessie's command and won against Dawn's Pachirisu.
In The Grass Menagerie!, Aipom was Ash's third and final Pokémon in his Eterna Gym Battle against Gardenia, she went up against Gardenia's Roserade after performing a contest like introduction. She used Double Team and began to get close to Roserade but Roserade used Grass Knot intending to trip Aipom up like Turtwig, although it destroyed the Double Team clones, Aipom herself was able to jump and avoid Grass Knot. Aipom then hit Roserade with Focus Punch, Roserade then used Magical Leaf but Aipom dodged by climbing on the trees. Using its vines, Roserade was able to grab Aipom using its vines. Roserade then used Flash blinding Aipom, making her unable to hit with her Focus Punch. Roserade then hit Aipom with Magical Leaf, initially panicking, Ash was able to calm down Aipom and got her to listen with her ears instead as she was still blind. Roserade used Weather Ball, which was Fire-type due to the harsh sunlight, Aipom was able to listen for the Weather Ball and she then hit the Weather Ball with Focus Punch, punching it back to Roserade, dealing super-effective damage. Roserade then used Magical Leaf but Aipom countered with Swift, opening her eyes as the effects of Flash had finished, the Swift then circled Roserade, then Aipom used Focus Punch on one of the Swift stars, knocking it into the Swift stars, causing them all to hit Roserade dealing major damage, Aipom then used the Focus Punch hitting Roserade, defeating the Bouquet Pokémon, winning Ash the Forest Badge.
In Throwing the Track Switch, Ash began the training for his next Gym battle in Veilstone City. However, Dawn's Buizel seemed to be more interested in Ash's battle training and thus couldn't set his mind on Dawn's training; meanwhile Ash's Aipom also had a problem in Ash's training because her style tended to be more Contest oriented. Then Zoey proposed that Ash and Dawn trade them. After some soul-searching, the Trainers agreed, and the trade took place.
In Journey to the Unown!, Aipom managed to learn Double Hit. Brock told Dawn that Aipom would evolve soon. Later in the episode, when Dawn and Aipom were being attacked by a group of Unown, Aipom jumped in and evolved into Ambipom.
In Team Shocker!, Dawn used Ambipom in the Appeals Round of the Solaceon Contest, but failed to advance to the Contest Battles. Zoey explained to Dawn that she failed due to an overuse of Swift, blocking Ambipom from view.
In Crossing the Battle Line!, Dawn used Ambipom in her Gym battle against Maylene. Ambipom was chosen for her extensive battling experience with Ash. She proved her strength in the battle by defeating Maylene's Meditite, making her the only Pokémon Dawn used in the match who managed to defeat one of Maylene's team. Despite this victory, Ambipom found herself unable to stand up to the strength of Maylene's Lucario and was quickly knocked out.
In Staging a Heroes Welcome, Dawn once again used Ambipom for the Appeal Round in the Wallace Cup. She managed to pass the round by dazzling the judges with Swift, Focus Punch, and Double Hit.
In Battling the Generation Gap! Dawn used her in the Battle Round of the Celestic Contest. Ambipom was able to easily defeat her first two opponents and then went up against Lila's Delcatty. Ambipom won the Contest by using combinations of its attacks instead of using only one attack at a time.
In Old Rivals, New Tricks, Ambipom was used in a Contest in Sandalstraw Town and was defeated by Kenny's Prinplup in the final round. During the Contest, she discovered a love and talent for ping pong. She used this talent to compete in the Pokémon Ping Pong Tournament with Dawn in To Thine Own Pokémon Be True. Due to her obvious natural ability, fellow competitor O offered her a place at his Ping Pong Training Center in Vermilion City. Dawn left the decision to Ambipom. After deciding to pursue Ping Pong over her love of Contests and Battles, Ambipom bid farewell to Dawn and Ash and left the group in order to follow her new ambition.