Zumi, internationally recognized as Siebold, holds dual prominence as a Kalos Elite Four member and a visionary chef who transforms Pokémon battles into culinary theater. His combat philosophy weaves gourmet terminology into strategic artistry, framing pivotal battle climaxes as the "main dish" of each encounter. His distinctive attire merges medieval grandeur with seafaring elements—a high-collared cloak drapes over a tailored uniform, accented by a cravat concealing a Key Stone and a pendant resembling a crystalline teardrop.

Blastoise anchors his team, evolving into Mega Blastoise to unleash the Mega Launcher ability, which intensifies pulse attacks like Hydro Pump and Dragon Pulse into torrential barrages. During a clash with Alain’s Mega Charizard X, Zumi initially questioned the challenger’s defiance of type advantages but later acknowledged Alain’s tactical ingenuity as the fiery opponent nearly overturned the battle. Though Mega Blastoise secured victory, Zumi commended Alain’s resilience, highlighting how the duel’s intensity mirrored a finely crafted tasting menu.

Unbeknownst to him, Zumi’s expertise in Mega Evolution became a covert asset to Lysandre’s ambitions, as the energy from such battles contributed to harnessing Zygarde’s power. Outside the Elite Four, Zumi’s restaurant stands as a dual-stage venue—where gastronomic excellence meets unranked battles, inviting trainers to savor both haute cuisine and strategic combat in equal measure.