Kidd Summers is a major character from the animated film Pokémon: Lucario and the Mystery of Mew. She is a renowned female adventurer who has achieved multiple world records, including the fastest trip around the world in a hot-air balloon, the deepest one-man submarine dive, and the longest independent space walk. Despite being raised in a sheltered or preppy environment, she developed a fearless and thrill-seeking personality.

Kidd first appears at Cameran Palace in the town of Rota, where she participates in the annual Aura Guardian Festival tournament to decide the Hero of the Year. She competes while dressed in traditional knight's armor, concealing her identity. She and one of her Weavile battle against Ash and his Pikachu in the final round, where they are defeated, and she subsequently reveals herself as a woman. After the tournament, she dances with Brock at the ceremonial ball but later slips away and changes into her normal outfit to pursue her true objective: researching the connection between the mythical Pokémon Mew and the Tree of Beginning.

Initially, her secretive behavior and her attempts to place a tracking device on Mew by sending her two Weavile from the palace roof make her appear suspicious, with Meowth even suggesting she might be a villain. However, as the story progresses, it becomes clear that her primary motivation is simply to conduct research and uncover the secrets of the Tree of Beginning. She eventually joins Ash and his friends on their journey to rescue Pikachu, who was taken to the Tree of Beginning by Mew, with the help of the aura Pokémon Lucario.

Kidd is backed by a high-tech organization commanded by Lieutenant Banks, who is the founder and inventor of various technological devices. She uses a pair of special sunglasses equipped with a camera, a map display, and a microphone for communication with Banks, to whom she transmits information about Mew, Lucario, and the Tree of Beginning. She also possesses small exploration robots that she uses to take samples upon reaching the Tree of Beginning. This research mission was initially undertaken because Banks's company was facing financial difficulties, and the intent was to profit from the discovery, but Kidd later decides to keep the Tree of Beginning a secret to protect its natural Pokémon environment.

Throughout her journey in the Tree of Beginning, Kidd demonstrates both courage and care for her Pokémon. When the Tree's immune system, which produces red blob-like antibodies to keep humans away, captures and absorbs her, she lets her Weavile out of their Poké Balls to keep them safe. She is later restored thanks to Mew. She also helps Mew when it falls ill due to the gradual destruction of the Tree of Beginning. After the Tree and Mew are saved, Banks tells Kidd that she could make a fortune by selling the story of her adventure, but she turns down this opportunity to keep the Tree safe from tourism and exploitation.

Kidd owns two Weavile, one of which battles in the tournament at Cameran Palace against Ash's Pikachu, using moves such as Shadow Ball and being defeated by Thunderbolt. She later sends both Weavile to attach a tracking device to Mew, but the mission fails because the Weavile are not very obedient and are stopped by the efforts of Ash and May's Pokémon. Despite scolding them for their disobedience, Kidd clearly cares for her Pokémon deeply, which is evident when she releases them to save them from the Tree of Beginning's antibodies and during their happy reunion afterward. At the end of the film, during the credits, she is seen waving goodbye to Ash and his friends as they depart on their journey. She is later shown visiting Forina alongside Butler and Diane from an earlier film, and she makes a brief cameo appearance in a montage in The Rise of Darkrai.