Bonnie (Japanese: ユリーカ Eureka) is a traveling companion of Ash who debuted in Kalos, Where Dreams and Adventures Begin! along with her older brother, Clemont.
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 in to 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.
In A Blustery Santalune Gym Battle!, Bonnie, Ash, and Clemont arrive at Santalune City and meet Viola, whom they later find out that she is the Gym Leader of the Santalune Gym. Upon seeing Viola's photos of Bug-type Pokémon, Bonnie becomes impressed and immediately asks Viola if she could marry Clemont, causing him to become embarrassed and drag her out of the Gym with his Aipom arm. Then, she, Clemont, and Alexa watch Ash's battle against Viola and also meet Serena, another Trainer. Later on, after Ash loses to Viola, she is properly introduced to Serena and then watches as Ash trains with Alexa for his upcoming rematch against Viola.
Later on, Bonnie continued to show her support for Ash in his training even though she was falling asleep, and prompting Clemont to put her to bed. The next day, she, Clemont, Serena, and Alexa cheered for Ash during his rematch and subsequent victory against Viola.
Bonnie is a young and cheerful girl who is always excited to meet new Pokémon. At times, she gets too invasive with Pokémon, similar to Iris, Burgundy and Bianca, causing them to attack her. She is very proud of her brother's accomplishments as an inventor, but sometimes criticizes him if his inventions do not work. For reasons currently unknown, she tries to find a wife for Clemont, first seen when she asks Viola and Jessica if they could marry her brother. This causes him to get embarrassed and remove her with his Aipom arm.
Bonnie dislikes feeling left out. Though she cannot own her own Pokémon, she participates in things that she can still do, such as refereeing unofficial matches. She also asks her brother permission to "keep" Pokémon that she one day wants to train, when she is old enough to be a Trainer. She enjoys taking care of these Pokémon and particularly likes brushing their fur, similar to a groomer. She always likes to be able to participate in the same activities the rest of the group are taking part in, and not being able to (such as in Battles in the Sky! when she was denied entry to the indoor sky diving facility), or otherwise being unable to get her own way, causes her to pout. These accomplishments may seem small but they are a way for Bonnie to occupy herself and continuously learn more about being a Trainer.
All in all, Bonnie is still a child. In Battling on Thin Ice!, she became tired easily and had to be put to bed early. In A Jolting Switcheroo!, she began to cry after she lost track of Dedenne. Ash and Serena had to help calm her down and encouraged her not to give up. In Splitting Heirs!, it was revealed that she dislikes carrots.