Bonnie was first seen with her brother Clemont in Lumiose City. Both were standing outside the Prism Tower when they watched Ash go inside to challenge the Lumiose Gym. When Ash was ejected out of the building, Clemont saved Ash with his Clemontic Gear while Bonnie saved Ash's Pikachu by catching him before he hit the ground. Thinking that he was cute, Bonnie hugged Pikachu, who shocked her in retaliation. Bonnie quickly apologized and explained that she is too young to have her own Pokémon and therefore always becomes excited when she meets one. Though she cannot own a Pokémon, she participates in other activities when she can. When Clemont and Ash had a battle against each other, she refereed the match for them. She later led them to Professor Sycamore's lab when Froakie was injured by Team Rocket.
In "Lumiose City Pursuit!", Bonnie met Professor Sycamore's Garchomp and played with the professor's other Pokémon, before Team Rocket infiltrated the lab. Bonnie tagged along with Ash and Clemont to help free the enraged Garchomp from the machine controlling her, and Bonnie watched her brother use one of his inventions to break into the Prism Tower.
In "A Battle of Aerial Mobility!", Bonnie and Clemont officially decided to accompany Ash on his journey through Kalos. Later in the episode, the group encountered a wild Dedenne. Bonnie asked Clemont to allow her to keep Dedenne, and Ash agreed. Bonnie tried to offer a berry to Dedenne, but a wild Fletchling stole the berry, scaring off Dedenne in the process. She later watched with her brother as Ash caught the Fletchling. After it was caught, Bonnie scolded Fletchling for stealing Dedenne's food but quickly forgave the Pokémon. Dedenne was later seen following Bonnie and the others.
Then, in "A Shockingly Cheeky Friendship!", Bonnie met the Dedenne from the previous episode when it stole the food she was trying to feed to Pikachu and Fletchling. She begged Clemont to capture it for her, but Dedenne forced the group to chase it in several holes in the ground, which caused Dedenne and Pikachu to get lost together. Eventually, Pikachu and Dedenne returned, but a previous encounter with Team Rocket left Dedenne exhausted to the point of fainting, much to Bonnie's horror. After Dedenne was rejuvenated by one of Clemont's inventions, it bonded with Clemont and helped defeat Team Rocket. Afterward, Dedenne allowed Clemont to capture it so that Bonnie could keep it in her satchel.
Bonnie has a great love for Pokémon. Despite her not being old enough to train Pokémon, she has strong ambitions and goals of being a trainer. She tends to forget she is the younger sibling and becomes very protective of her older brother Clemont. As a result, she'll often look for a beautiful girl to be her brother's wife, much to his chagrin. She is sometimes annoyed with his over-protectiveness and nagging, but she understands that he loves her very much, and she returns these affections. When frightened or stressed, Bonnie will reach for her brother's hand, or hide behind him, thus displaying a keen element of trust in their relationship.
Besides Clemont, Bonnie also has a sisterly relationship with Serena, likely because of the fact that they are the only girls in the group and thus share similar interests. This is corroborated in Day Three Blockbusters! where she assisted Serena in the kitchen making Poké Puffs. In turn, Serena often does little fashion-related favors for Bonnie, acting in the role of the cooler older sister.
Bonnie enjoys caring for Pokémon and is very protective of those under her care. She is curious and enthusiastic when encountering new Pokémon as well.
She is a small and slender young girl with shiny golden-blonde hair tied in a side ponytail with an orange band, and sky blue eyes. She wears a brown short-sleeved top with a soft black bow on the neckline, knee-length black compression shorts covered by a puffy white skirt resembling a cloud, some pink colored Mary-Jane shoes on her feet and a yellow shoulder bag. After meeting Squishy, Bonnie's bag has been sewn with an extra slot to hold Squishy (a Zygarde Core) in.
- Whenever she sees a beautiful girl who she thinks would be Clemont's girlfriend, she tries to pair her with Clemont. Because of this, she shares some similarities with Brock, but they have also some differences - while Brock directly tries to impress the beautiful girl he falls in love with (mainly Officer Jenny and \ or Nurse Joy), Bonnie tries to pair the beautiful girl to Clemont. In Addition, both she and Brock get dragged by another character (Misty, Max or Croagunk in Brock's case, and Clemont in Bonnie's case).
- She also shares some similarities with Max, as both Bonnie and Max are traveling companions who are too young to have a Pokemon. However, Bonnie takes care of Dedenne.