She is voiced by Mayuki Makiguchi in the Japanese version, and Haven Paschall in the English version of the anime.
During the first episode, she was very sassy and rebellious towards her own mother and formerly hated Rhyhorn racing. However, she later proves herself to be very kind and polite, being able to get along with others pretty well and has shown concern for others (her friends).
She loves fashion and is particular about her appearance (she even adopted the habit of picking the outfit her mother won't choose). Serena is skilled in baking, making her cookies/Poké Puffs for both her friends and the other Pokémon. She hates to be wet or muddy.
One thing that shines about her character is her deep affection towards Ash, ever since he saved her from a wild Poliwag and guided her back to the campsite. Even as the years passed since then, she still recognizes him (after watching him on television), and embarked on a journey to find him (returning the handkerchief). Serena admires his sense of determination and takes his advice to heart, and often encourages him in his battles. She also blushes when looking at or talking to him. At the end of their journey before leaving for Hoenn, Serena ultimately musters up the courage to kiss Ash Ketchum while promising to become a more remarkable lady for him when they meet again.
At first, she was uncertain of her goal but in Dreaming a Performer's Dream, she decided to become a top-class Pokémon Performer (with the title of Kalos Queen) and hoping to one day face-off against Aria (the current Kalos Queen).
According to the anime, she appears to have known Ash Ketchum before and have been childhood friends with him ever since. Serena met Ash at the time they attended Professor Oak's Pokémon summer camp in Pallet Town. During that time, she got lost in the middle of a forest while trying to find her group. Just then, a wild Poliwag jumped out of the bushes and scared her, causing her to fall on the ground and hurt her knee. Scared and upset, she called out for her mother for help. But moments later, Ash came out of the bushes calling for Poliwag. He was also wondering through the forest looking for the same Poliwag. While he was looking for it, he stumbled upon the young and frightened girl. Seeing how incredibly hurt she is, he bandages her knee up with his clean, blue handkerchief. Then he lent her his hand, warning her to not give up till it's over, and helped her stand up on her feet. After that, he escorted her back to the campsite. Ever since their first encounter, Serena developed romantic feelings for him and she kept the handkerchief as a reminder of the day she first met Ash.
Pokemon X and Y
In the Pokemon X and Y video games, Serena has honey hair with grey eyes and wears a dark pink hat with a black hatband and white sunglasses. She also wears a black tank top, a red double waist side buttons pleated skirt, black thigh high stockings, and black sneakers with a pink semi-circle on it. She carries around a pink bag with black decals on it. She has a Mega Ring on her left wrist.
Serena's first outfit in the anime consisted of a grayish-black tank-top with a white collar, a red double waist side buttons pleated skirt, a dark pink hat with a black bow and hatband, black stockings, and black shoes.
Anime (XY060-XYZ Series)
Serena's second, current and main outfit in the anime consists of a light pink dress over a grayish-black tank-top with a white-collar. The dress is tied at the collar with a blue ribbon that Ash gave her in "Under the Pledging Tree!". Over her dress, she wears a long red vest with large pockets. She also wears black stockings and brown boots. On her head, she wears a pink-red fedora with a black hatband.
- In Giving Chase at the Rhyhorn Race!, during her flashbacks that show her childhood with Ash, Serena wore a straw hat with a pink bow tied around it and a pink dress with pink shoes.
- In "Battling at Full Volume!", Serena posed as Ash by wearing his clothing.
In the games
Serena has a counterpart with the same name which is the female player in the Pokémon X and Y games. Her male counterpart is Calem.
As the player
Serena is a young girl who lives in Vaniville Town with her mother, Grace and her friends Tierno, Trevor, Shauna and her next-door neighbor Calem. The five of them form a bond almost instantaneously and they decide to go on their Pokémon adventures together.
As an NPC
When she is not selected by the player, she will appear as the player's rival. She will select the starter that is strong against the player (Fennekin if the player chose Chespin, Froakie if the player chose Fennekin and Chespin if the player chose Froakie), while Shauna will choose the remaining starter. Regardless of the rival's gender, one of them (the other being Calem) will catch themselves an Absol which would later go on to gain the ability to Mega Evolve during the final rival battle during the post-game.
Also, unlike her anime counterpart and her player counterpart, she ties her hair in a ponytail and does not wear a hat.
In the manga
Serena has a counterpart named Y, who is a Sky Trainer. She is friends with X, Shauna, Tierno, and Trevor. She tried to get X to leave his house but she failed. X then decided to go on a journey with the others after Xerneas and Yveltal went on a rampage on their hometown, Vaniville Town. Her full name is Yvonne Gabena.
Pokémon (anime only)
- Rhyhorn (Diancie and the Cocoon of Destruction and "A Race for Home!").
- Skiddo ("A Race for Home!").
- Goomy ("One for the Goomy!").
- Frogadier ("So You're Having a Bad Day!").
- Chespin ("So You're Having a Bad Day!").
- Mamoswine ("Over the Mountain of Snow!").
- Pikachu ("Battling at Full Volume!").
- Talonflame (Volcanion and the Mechanical Marvel).
- She is the only female traveling companion to have a canonical crush on Ash, and also the first female companion to kiss Ash. Interestingly, she is the first one to know him before the start of the series. Whenever it has been openly discussed with her by another character, rather than attempting to deny it, Serena instead blushes and acts embarrassed.
- She is also the only female traveling companion who never got into an argument with Ash on a regular basis or was easily irritated by his actions, as Misty, May, Dawn (on a smaller extent) and Iris have all been easily irritated by his recklessness and have argued with him during their travels with him. The only time both Ash and Serena ever argued was in "Seeing the Forest for the Trees!", but it was over a serious matter instead of childish matters.
- Unlike Ash's other female-traveling companions, she was personally invited by him to join. She was also the only one to not get shocked by his Pikachu (nor does she own a bike).
- Serena's physical change later in the series reflects the Japanese tradition involving women cutting their hair short to signify their new-found resolve.
- It may also be a reference to how the XY games are the first time players can customize their character.
- Serena's Pancham is the only Pokémon she has that is a male. Also, her Sylveon is the very first Pokémon owned by the main character to be a pure Fairy-Type (not counting Clemont's Dedenne which is a dual Fairy/Electric-type).
- Serena shares a lot of characteristics with May from the Advanced Generation series:
- Neither knew what their goal was at first but eventually focused on one related to beauty and style.
- Both chose the Fire-Type starter: Torchic in May's case and Fennekin in Serena's.
- Both have caught a Pokémon based on a bear: Munchlax and Pancham, respectively.
- Both have obtained an Eevee that has evolved. (A Glaceon and Sylveon, respectively).
- Both were expected to have the same career as one of their parents (a Gym Leader and Rhyhorn Racer respectively), neither of which they wanted to pursue.
- Both girls pay attention to fashion, albeit in different areas: May focuses more on swimsuits while Serena focuses on outerwear.
- Serena also shares some characteristics with Dawn from the Diamond and Pearl series:
- Their starter Pokémon defended them from wild Bug-type Pokémon (Fennekin defended Serena from a Vespiquen and Piplup defended Dawn from an Ariados).
- They both become renowned through media (PokéVision and Showcases for Serena and The Wallace Cup for Dawn).
- They both had a large number of rivals in their professions for the top spot.
- Since the beginning (especially when they first meet), they both had great admiration for Ash and his actions out of love for Pokémon (when Ash helped an agitated Garchomp on Prism Tower on live TV for Serena and when he rescued Pikachu by climbing one of Team Rocket's mechas for Dawn), and are never judgmental of and very kind to him, even going as far as always believing in Ash to win his battles.