As a Fennekin, it first appeared in A Battle of Aerial Mobility! as one of the three starter Pokémon new Pokémon Trainers could choose from Professor Sycamore. In A Shockingly Cheeky Friendship!, Serena chose Fennekin as her starter Pokémon. Later in the same episode, Fennekin chased a wild Vespiquen that was about to attack Serena away with Ember, demonstrating courage and care for her Trainer.
In A Blustery Santalune Gym Battle!, Fennekin woke up with Serena at a Pokémon Center and enjoyed a large breakfast with her. Fennekin mimicked Serena's actions during their breakfast by stretching as the same time she did. Later in the same episode, she was introduced to Ash, Pikachu, Clemont, and Bonnie and greeted them happily.
In Giving Chase at the Rhyhorn Race!, it was first seen when Serena baked cookies, it mimicked her trainers actions again. Later Fennekin had her first battle, fighting against Team Rocket and using Ember to blast them off. Later Serena introduced her to Grace, her mother, revealing to her that Fennekin was her choice of starter Pokémon.
In Grooming Furfrou!, Serena left her with what she thought were Pokémon Stylists so she could be groomed. Unfortunately, the "Pokémon Stylists" turned out to be Team Rocket, who were running a scam to steal Pokémon. When Serena saw the "Pokémon Stylists" on a wanted poster, she rushed to rescue Fennekin with the help of Ash, Pikachu, Jessica and her Furfrou. Fennekin was rescued and reunited with her Trainer after Team Rocket was sent blasting off.
In The Bamboozling Forest!, whilst enjoying lunch, she along with Pikachu, Froakie and Chespin, were kidnapped by Team Rocket, those the net broke free and were separated due to Team Rocket's squabblings. When she landed her tail became dirty upsetting her, whilst trying to clean it, she was found by the others as well as Meowth, and tried to hide her dirty tail from the others, though Froakie used its Frubbles to tidy it. Later after she and the others were reunited with their trainers, she went with them to find a bamboo shoot for Pangoro since Chespin destroyed its first. Later after being attacked by Jessie's new Pokémon Pumpkaboo and was caught and drained by Leech Seed, she helped protect Ash from Team Rocket's attacks by using her Ember. She was freed when Pangoro was rescued and defeated Team Rocket.
In A PokéVision of Things to Come!, she became jealous of Aria and her Fennekin after she observed their winning PR video. Serena was inspired by the video, and she and Fennekin decided to make their own. While filming the video, Pikachu accidentally spilled flour on Fennekin. This angered her and she attempted to attack Pikachu with Ember, but he dodged and Ash got hit instead. Fennekin was later captured by Team Rocket alongside Pikachu and Dedenne but managed to escape with their combined attacks, including her Hidden Power. Later, Fennekin hesitated to run through a large muddy puddle that was between herself and Serena, showing her dislike of water. However, after seeing her trainer running to save her and getting attacked by Team Rocket, Fennekin ran to protect her by unleashing a Flamethrower attack at the villains.
In A Battle by Any Other Name!, Serena competed with Fennekin in a Poké Puff Contest against her new rival Miette. They made a Fire-type style Poké Puff with a twig on the top due to Fennekin's affinity for twigs. Later, they went looking in a forest for ingredients but were attacked by a group of angry Swirlix. Fennekin tried to ward off the Swirlix with Scratch, but she was entangled in the Swirlix's white sticky thread and became stuck until she was rescued by Pikachu's Thunderbolt. She then drove them off with Flamethrower. Later, she combined her attack with Slurpuff's Energy Ball and Pikachu's Thunderbolt to destroy Team Rocket's mecha. Afterwards, she helped in the final round of the Poké Puff Contest but lost to the Berrybaker kids along with Miette.
In Summer of Discovery!, Fennekin had a battle against Shauna's Bulbasaur. Fennekin started off with a Flamethrower and Bulbasaur countered with an Energy Ball. Despite having the type advantage, the Energy Ball hit and Fennekin lost the battle because of the First-Touch-Rule.
In Battling Into the Hall of Fame!, Fennekin was used in a Tag Battle alongside Ash's Pikachu and Clemont's Chespin against Shauna's Bulbasaur, Tierno's Squirtle and Trevor's Charmander. Fennekin started by using her Flamethrower to counter Charmander's Flamethrower so Pikachu could attack Squirtle. Squirtle managed to knock Pikachu away and hit Fennekin with a super-effective Water Gun. Fennekin later tried to block Squirtle's Aqua Tail with Hidden Power, but Aqua Tail overpowered her attack and Fennekin was defeated. She was initially disappointed after losing but later cheered up.
In Dreaming a Performer's Dream!, Fennekin watched a Rookie Class Pokémon Showcase with her Trainer as well as Shauna and her Bulbasaur, watching Aria and her Braixen as well as Kayleigh's performance, until it was interrupted by a Pancham, later she looked for Chespin after it chased after the same Pancham. She found Pancham and led Serena to it. After a while, Serena decided to capture Pancham since it liked performing and Serena wanted to be a Pokémon Performer, so Fennekin battled Pancham, it went for a Scratch but was captured Team Rocket, as Jessie wanted a Braixen like Aria. However she was rescued thanks to the efforts of Fletchinder, Pancham and Chespin. And Team Rocket was sent away by Pikachu, Fennekin and Pancham battled again, although Pancham was strong and evaded capture once, she defeated it with Flamethrower and Hidden Power which allowed Serena to capture Pancham. She was later seen when Serena was announcing her dream to Fennekin and Pancham.
In Pathways to Performance Partnering!, Fennekin performed with Pancham when Serena was demonstrating to her friends and Nini. She used Flamethrower to create Fire Rings whilst Pancham jumped through them. To end their performance, Fennenkin used Flamethrower whilst Pancham used Dark Pulse to create a magnificant firestorm. Nini mentioned Pancham's movements weren't compatible with Fennekin's dance. After performing in Jessie's dancing training, she was captured along with Pancham and Chespin as well as Nini's Smoochum and Farfetch'd, in a balloon by Team Rocket, but it broke after Chespin and Pancham fought again. Whilst escaping she was not impressed with Pancham and Chespin's squabbling, after being found by Team Rocket, she was defeated by Pumpkaboo's Shadow Ball but was saved when Chespin and Pancham, who had been squabbling for a while, temporarily teamed up to defeat Team Rocket. She was later reunited with her Trainer.
In XY064, Serena began training Fennekin and Pancham for a new technique for their next Pokémon Showcase, it initially went well, however it failed when Pancham missed Fennekin's Fire Ring and burned itself, causing Pancham to become angry towards Fennekin who also became angry and they became ambivalent towards each other, another attempt at the Fire Ring failed, causing Pancham to crash into Fennekin, their fighting caused Fennekin to hit Serena with a Flamethrower. Serena became angry at them causing them to stop and in her frustration, she ran away, upsetting Fennekin and Pancham for most of the day. She was happy when she returned. After apologizing to each other, Serena and Aria had a Performance Double Battle, using Fennekin and Pancham against Aria's Delphox and Aromatisse. She struggled against Aromatisse with her Scratch being blocked with Reflect and Pancham being hit with Mystical Fire, after Stone Edge was blocked by reflect, after some advice from Aria, Serena decided to combine their moves with Fennekin using Pancham's Stone Edge to climb up and launch a Flamethrower from the air, but this was countered and overpowered by Delphox's Flamethrower, injuring her, afterwards Pancham tried to blocked Aromatisse's Charge Beam attack on her with Dark Pulse, but it was being overpowered, after some words of encouragement from Serena, she evolved into Braixen. Braixen launched Flamethrower whilst Pancham launched Dark Pulse, dealing major damage to Delphox and Aromatisse, but Aria was called away, cancelling their battle.