Daigo Tsuwabuki, internationally known as Steven Stone, is the son of the Devon Corporation president. This major company develops Pokémon-related technology and research. Steven holds the title of Hoenn Region Champion, specializing in Steel-type Pokémon while also favoring Rock-types due to his deep personal fascination with rare stones and minerals. His battle team often features Metagross, Aggron, and Cradily. He maintains a calm, wise, and knowledgeable demeanor, showing humility despite his wealth and status. Generally quiet and solitary, Steven possesses a notable passion for collecting and studying rare stones and rocks, extending to a dedicated interest in Mega Stones and Mega Evolution mechanics. Over time, he demonstrates greater openness to collaboration, engaging with other trainers and researchers. His significant activities involve researching Mega Evolution's origins. He actively pursues its roots, deciphering ancient texts like a wooden plate prophecy indicating that "the glimmer of two stones" reveals the path to a legendary megalith. This quest leads him to partner with Alain; using their Key Stones together, they activate ancient mechanisms to uncover hidden paths and the powerful Giant Rock artifact, linked to Primal Reversion and Legendary Pokémon Groudon, Kyogre, and Rayquaza. During events including Mega Evolution Special IV, Steven travels to Kalos with Alain and Mairin after the Giant Rock vanishes. At Lysandre Labs, he examines the secured Giant Rock, contained within a specialized energy-dampening tank to prevent it from attracting the Legendary weather trio. He also expresses concern for Mairin and her Chespie, who fell into a coma due to unstable energy exposure during an experiment involving mysterious creatures. Steven remains present during discussions analyzing the Giant Rock's properties and Alain's battles. Beyond the Mega Evolution Specials, he appears throughout the Hoenn region games. He assists the player character by providing items such as the Devon Scope and HM08 Dive, and aids during crises involving Groudon or Kyogre. In Pokémon Emerald, no longer Champion, he assists against Team Magma and can be battled post-game at Meteor Falls. He also appears in other regions like Kanto and Johto, gifting the player a Beldum or a Hoenn starter Pokémon.