Known as Delion in German localization, Leon in English, and Dande (ダンデ) in Japanese media, he reigns as Champion of the Galar region. He earned this title during his very first Gym Challenge, demolishing every opponent without a single defeat. His legendary winning streak remains unbroken, cementing his reputation as Galar's strongest Trainer. His battle style is intensely unpredictable, always going "all out," a strategy that commands widespread admiration across Galar.

His partner Charizard stands at the heart of his victories and battle strategy. Their formidable bond proved decisive in the Pokémon World Championships finals, where he defeated Kanto Champion Lance. Both Dynamaxed their Pokémon in the climactic clash, but his Charizard triumphed, securing his position as world champion.

He shares a close childhood friendship with Sonia, now training to become a Pokémon Professor, who first taught him about Pokémon battles. His natural talent quickly eclipsed hers once he began his own journey, influencing her shift from battling to academia. He also has a younger brother, Hop, who is pursuing his own path as a Trainer. Unconfirmed whispers suggest both brothers might be descendants of the historical figure Professor Laventon.

His powerful team features Charizard, Aegislash, Cinderace, Dragapult, Haxorus, Inteleon, Mr. Rime, Rillaboom, and even the Legendary Pokémon Eternatus.