Misty's first appearance was in the very first episode of the anime series, Pokémon - I Choose You! In this episode, she first meets Ash after fishing him out of the water when he was trying to get away from Spearow. Ash then takes Misty's bike from her in order to escape the Spearow, which is then wrecked by Pikachu'sThunderShock. Misty then tracks down Ash and follows him around on his adventures until he can pay her back. She eventually forgets about the bike and becomes one of Ash's closest friends. She is also the Cerulean CityGym Leader.
In the series, Misty first is seen wearing a yellow tank top with red suspenders and light blue denim shorts. Her shoes were colored red and white, with a yellow streak in the middle. Misty's personality in the anime can be very complex at times. She can be very nice to her friends but will then quickly change moods in a short amount of time, particularly anger. She is quite proficient in anything having to do with water as can be seen in certain episodes where she has ability in fishing, swimming, and overall Water Pokémon training. Even though she wanted to stay with Ash, Misty felt obligated to watch over the Gym. The two went their separate ways, and Misty became the official Gym Leader at Cerulean City's Gym.
Misty's second costume is later shown after she meets up with the main group in Hoenn, after she had already left. Here she wears a yellow, sleeveless jacket with a blue collar, and a large blue button. She also wears short, form-fitting shorts that is connected to a crimson colored upper body piece, which may be a swimsuit. Her shoes are now light and burnt orange.
Misty has only appeared as a guest star in the remainder of the Pokémon series. In one of her cameo appearances in the Advanced Generation series, her Togepievolves into Togetic. Misty releases Togetic after it chooses to stay behind to defend the Mirage Kingdom. After Ash finishes competing in the Hoenn League, he returns home to Pallet Town to find Misty waiting for him. However, she isn't the only one to rejoin Ash, as May, Max, and Brock join him as well for the Battle Frontier challenges. She travels with Ash for two episodes, and shortly after returns to her Gym.
Misty has a slight inferiority complex, mostly due to her three sisters Daisy, Lily, and Violet who formed the group, "The Three Sensational Sisters" (their synchronized swimming group), and refer to Misty as the "runt"or "weaker one". This complex diminishes over time as Misty grows closer to Daisy, her oldest sister.
Until Misty became the Cerulean City Gym Leader, her three older sisters were the ones who ran the gym, although when Ash came along to get his Cascade Badge, it was Misty who battled him for it.
Despite being the youngest of four daughters, Misty's the smartest and the most mature and responsible of her sisters, with her second-from-oldest sister, Violet, being the next smartest and next most mature and responsible.
Misty specializes mainly in Water-type Pokémon, which are her favorite type of Pokémon, and she aims to become a world-class Water-type Pokémon trainer. However, Misty has had other types of Pokémon. Her least favorite type of Pokémon are Bug-type Pokémon, as she has a deep-rooted fear of them, although this lessens over the course of the series, but not to the point where's totally gotten over her fear, as shown in A Real Cleffa Hanger.
As the series continues, she gradually shows herself to be kind and sensible. She restrains Brock from girls, often pulling him away by the ear. Her well-trained Pokémon reflect her aspiration to become a top trainer. She admires the Ice-type trainer Lorelei.
She is currently the leader for the Cerulean City Gym. She loves Water-types and usually only trains them.
Misty's Goldeen is a Pokémon Misty caught in Kanto. It still resides with her in the Cerulean Gym. Goldeen is one of Misty's favorite Pokémon.
Misty's Politoed is one of Misty's Pokémon that she caught in the Orange Islands as a Poliwag. It evolved from a Poliwag to Poliwhirl in "The Totodile Duel" and evolved again from Poliwhirl to Politoed in "Outrageous Fortunes" when it accidentally touched a King's Rock, causing it to evolve. It currently resides in the Cerulean Gym with Misty.
Ash found it as an egg and soon it hatched into a Togepi. Ash wanted it, but Togepi liked Misty, so it chose Misty. When Misty visited Ash on his Hoenn journey, Team Rocket invaded and Togepi evolved into Togetic. Misty left it to protect the Togepi Kingdom in the episode of Togepi Mirage.
Misty is the first victim of the recurring gag in the anime where Ash's Pikachu destroys every main female character's bike. This gag was also transferred to May and Dawn. However, this gag did not affect Iris or Serena, because they did not have bikes.
She also has a fear on Gyarados after crawling into its mouth as a baby, despite it is part Water-type. She overcame this fear and she had a Gyarados on her own that knows Flamethrower.
Misty was the one who originated the gag of pulling Brock away from pretty women. She pulled Brock on the ear every time he flirted with a pretty woman. This gag transferred to Max in Hoenn and then Brock's Croagunk in Sinnoh (though Croagunk used Poison Jab instead of pulling Brock's ear).
Misty originally called Ash's Caterpie "ugly" and "disgusting"; Ash later attempted to leave Misty only to have her secretly following him. Once it evolved to Butterfree she warmed up to it.
Misty has three things she has a strong dislike for. They are carrots, peppers, and bugs stated in episode 3 of the first series.
In the second Pokémon movie, Misty got jealous after Melody kisses Ash. However, she denied having a crush on Ash.
Misty is the only female main character to appear in more than one generation as she appeared in Generation I and II as a main character, while May, Dawn, and Iris have appeared in only one generation as a main character.
Misty adopts a different personality when talking about/interacting with water Pokémon, as noted by Ash in the episode Tentacool & Tentacruel.