TV Special
Description
Daigo Tsuwabuki, internationally known as Steven Stone, is the son of the Devon Corporation president. He holds the title of Hoenn League Champion, specializing in Steel-type Pokémon, with his Metagross as his team's cornerstone. A tall young man, he has steel-blue hair and matching eyes. His signature attire includes a charcoal jacket featuring black zig-zag stripes, a white undershirt, a red tie, skinny black pants, and black low-heeled shoes, adorned with metallic jewelry on sleeves and fingers. Later appearances show him wearing a Mega Stickpin on his jacket, functioning as his Key Stone.

His personality blends wisdom and humility despite his youth. Typically calm, reserved, and solitary, he grows more open to collaboration, evidenced in his dealings with Alain. He possesses a deep appreciation for rare stones and minerals, collecting them as a hobby. While generally playful and composed, he demonstrates seriousness in crises, confronting primal threats like Groudon and Kyogre or Lysandre's revelations. He exhibits strong confidence in his Pokémon and values others' efforts, showing respect toward fellow Champions.

His background involves stepping down as Champion in some continuities while retaining the title in others. He travels extensively, often floating and traversing regions using his Metagross's magnetism. Entrusted by his father with Devon Corporation security missions, he sealed the Seafloor Cavern to prevent Groudon and Kyogre's awakening. During this conflict, he awakened and controlled Registeel alongside the Hoenn Elite Four to contain the Legendary Pokémon clash. This effort caused his apparent death due to immense strain, though he was later revived under unexplained circumstances. Subsequently, he researched Mega Evolution, becoming Gurkinn's successor at the Tower of Mastery and distributing Key Stones and Mega Bracelets to allies like Ruby and Emerald to combat new threats.

His key Pokémon are a Shiny Metagross capable of Mega Evolution, Aggron, Aron, and Cradily. He once owned a Beldum, which he gave away. Metagross remains his primary partner, frequently used for transportation and battle.

In the Mega Evolution Specials, he investigated ancient ruins linked to Mega Evolution, deciphering a wooden plate referencing a "megalith." Alongside Alain, he activated a mechanism with their Key Stones, unveiling a staircase to the Giant Rock. This artifact attracted a Mega Rayquaza that overpowered them. Later, after the Giant Rock vanished, he brought Alain and Mairin to Devon Corporation headquarters in Rustboro City. Lysandre alerted them to Primal Groudon's emergence roughly 200 kilometers off Kanazumi City's coast. Recalling myths of Primal Reversion, he warned of catastrophic consequences if Groudon and Kyogre clashed and joined Alain for an aerial survey. During this event, he Mega Evolved Metagross to fend off the rampaging Legendary Pokémon.

In other media, he encountered Ruby in Granite Cave, saving him from wild Mawile using his Beldum, Metang, and Metagross. He later coordinated with the Elite Four and Wallace during Hoenn's crisis, sacrificing himself to control Registeel. Post-revival, he sold his Sinnoh villa to return to Hoenn, focusing on stone collection and Devon Corporation missions.