Fennekin first appeared as one of the three starter Pokémon new trainers can choose from Professor Sycamore, and was chosen by Serena as her starter Pokémon. Later on at the end of the fourth episode, a wild Vespiquen attacked Serena and Fennekin, who mistook it for a person. But Fennekin protected her trainer by scaring it away with an Ember attack. After joining Ash, Clemont, and Bonnie on their journey, Fennekin was used in its first Pokémon battle to help Serena to save Ash, Pikachu, and the Rhyhorn from Team Rocket.
Fennekin later helped Serena prepare a video performance called PokéVision. But during the filming, Fennekin was taken away by Team Rocket and her trainer and her friends went off to find and save her. When they found her along with Pikachu and Dedenne, Fennekin was hesitant to walk across the mud puddle because of her fear of being untidy. However, when she saw how Serena bravely risking her life to save her, she found the courage to run across the puddle to reach her trainer. In the battle against Team Rocket, she learned Flamethrower and sent them blasting off. After Team Rocket blasted off, Fennekin and Serena managed to finish the video and broadcast it just in time.
Later, Fennekin and Serena both participated in the Poké Puff Contest and were competing against Miette and her Slurpuff. But the contest was interrupted when Team Rocket stole the ingredients. Serena, Fennekin and their friends went off to look for the ingredients until they were ambushed by a group of angry Swirlix. Fennekin tried to protect Serena ended up getting entangled in Swirlix's sticky thread, but was eventually rescued by Ash and his Pikachu. She then scared the Swirlix away with a Flamethrower. When the gang were fighting against Team Rocket, she combined her attacks with Slurpuff and Pikachu and sent them flying. With the ingredients retrieved and returned, she helped Serena in the final round of the contest, but lost against the Berrybaker kids.
She was later used in Pokémon battle against Serena's rival Shauna and her Bulbasaur. Fennekin launched a strong Flamethrower but was countered with a close range Energy Ball. Astounded with Bulbasaur's power despite its type disadvantage, Serena and Fennekin lost the battle due to the First-Touch rule.
Later, Fennekin watched a Pokémon Showcase with Serena, Shauna, and Bulbasaur and got to see Aria, the Kalos Queen, and her Braixen in person for the first time. They were incredibly amazed at Aria's performance and it inspired Fennekin and Serena to compete in Pokémon Showcases. But when another trainer named Kayleigh and her Furfrou went to have a turn to perform, a wild Pancham suddenly appeared dancing on the stage and interrupted the show. Fennekin later tracked down Pancham and learned that Pancham has a dream of becoming a great performer. Fennekin decided to help Serena catch it, but during the battle, she ended up getting caught by Team Rocket. But after the brave heroics of Fletchinder, Chespin, Pikachu, Dedenne, and Pancham, Team Rocket was sent blasting off. Fennekin and Pancham resumed the battle, and Fennekin managed to defeated Pancham with Flamethrower and Hidden Power, thus allowing Serena to successfully catch Pancham.
Fennekin participated alongside Serena in the Coumarine Rookie Class Showcase. Unfortunately during the first round performance, Fennekin tripped over a bow from her outfit Serena decorated for her. This eliminated them from the showcase, leaving Fennekin saddened and mortified, but Serena calmly reassured her. When Serena began to cry the following morning, Fennekin tearfully tried to lift her trainer's spirits, ultimately forcing her into a hug alongside Pancham. She and Pancham watched as Serena cut her hair and cheerfully presented her new appearance to Ash, Pikachu, Clemont, and Bonnie later on.
It later used its Scratch attack to free Dedenne from a Pokémon Hunter's cage. Later in the same episode Serena and Fennekin battled alongside Ash, Pikachu and Team Rocket and their Pokémon against the Pokémon Hunter and his Rhyperior, contributing her Flamethrower attack to form a maelstrom of energy to knock out the perpetrators.
After watching a video of Shauna's performance in the Coumarine City Showcase, Serena was determined to train more with both Fennekin and Pancham. Their practice was riddled with difficulty however when at first Fennekin accidentally burned Pancham and again when the latter accidentally fell on the former. When things started heating up between the two, Serena tried to intervene as Pancham antagonized Fennekin from its position on her shoulders. Fennekin had enough and used Flamethrower, aiming for Pancham but ending up burning Serena instead. After Serena lost her temper, snapped at them and left in a state of shame for doing so, Fennekin stood with Pancham by the window worrying about her as Ash attempted to relieve their concerns. When Serena returned to apologize to her Pokémon, Fennekin happily jumped into her arms to welcome her back. Later, during Serena's double battle against a disguised Aria, Fennekin started out with Scratch only to be deflected by Aria's Aromatisse. When the chips started looking down, Pancham protected Fennekin from an oncoming Flamethrower from Aria's Delphox Serena remembered something Aria had told her earlier and assured her Pokémon things would be fine. Fennekin saw this and began to glow: she grew two feet in height, her tail lengthened and became bushier, she gained a stick in her tail with which to use her Fire-type moves and most noticeably (besides the height thing), her front legs developed into arms. When the light faded, everyone recognized Fennekin as having evolved into Braixen. After Aria had to leave following an abrupt phone call, Serena hugged her Pokémon, their quarrel all done.
When Serena, Ash and Bonnie arrive to meet Clemont, Serena showed him her newly evolved Braixen. She later watched Ash and Clemont battling and cheering for both trainers. Later, Braixen was watching the fashion art with her trainer and Bonnie and joined them in fashion show. She later watched a video and learned with Serena and Panchum about the next perform and it's next location.
Braixen got prepared for the next performance. Despite Serena's dress getting toren and gotten shorten to get fix, they managed to pull through and pulled off a great performance, allowing Serena to win.
While Serena and her Pokémon perform for their next performance, Braixen's twig gets broken, hurting her. The other tried to get a new twig for her, but she turned them down, as she would never replace her twig. They visit a woods carer named Woodward, hoping he would help with something with the broken twig. Whilst battling to figure out what to do, Team Rocket attacks. Braixen and Pancham do a performance attack where she soon learned Fire Blast and defeats Team Rocket, but in the process her twig gets broken into more pieces. Pancham soon gives Braixen a new twig and she accepts it. Serena then puts a bow on it as an addition to remember her old twig. The gang then ties her twig pieces to lay them to rest just as the gang left for their next destination.
Fennekin is a very friendly and kindhearted Pokémon with a very bold heart. She tends to mimic Serena as shown when it stretched like her. Like her trainer, she detests getting dirty, and always takes great care to look her best at all times, and can get angry if she gets dirty. However, she overcomes her fear of untidiness in order to protect Serena, though she never loses her desire to be beautiful. Fennekin can sometimes be very temperamental with other trainers and their Pokémon but she always obeys Serena, and is quite affectionate towards her. When she is Braixen she is shown to be the same as she was back as Fennekin. It was seen in Mending a Broken Spirit! that she was very attached to her twig when it broke and was very picky when her friends tried to find a replacement.
|Ember||A Shockingly Cheeky Friendship!|
|Hidden Power +||A PokéVision of Things to Come!|
|Flamethrower +||A PokéVision of Things to Come!|
|Scratch +||A Battle by Any Other Name!*|
|Fire Blast +||Mending a Broken Spirit!|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.
- Braixen is Serena's first evolved Pokémon.
- Along with Serena's other two Pokémon, Braixen enjoys a certain aspect of Pokémon Performing. In Braixen's case, it's dressing up and performing as well.