Ninja Riot, a professional thief, teams with Marilyn Flame to hunt the Mythical Pokémon Diancie, coveting its diamond-generating powers. Relying on stealth and combat expertise, he commands a Greninja skilled in Water Shuriken and Tongue Wrap to ensnare targets. Their partnership thrives on sharp banter and rivalry, his stoic reserve contrasting Marilyn’s fiery expressiveness.

Pursuing Diancie pits them against rival thieves Millis Steel, Argus Steel, and Ash’s group. Greninja’s clone techniques and ambush tactics prove formidable, culminating in Diancie’s capture during a forest skirmish—an act that accidentally ruptures Yveltal’s cocoon, unleashing the Legendary Pokémon’s destructive rampage.

When Yveltal petrifies Greninja and other Pokémon, Ninja Riot’s composed facade shatters, exposing genuine anguish over his partner’s fate. This vulnerability sparks a shift in allegiance, driving him to ally with Marilyn against Yveltal, though their efforts falter. Following Xerneas’s life-restoring intervention, the duo abandons thievery, their rivalry softening into mutual affection. They share an embrace before petrification and, upon revival, retire to peaceful lives, later sealing their redemption through engagement.

Clad in Greninja-inspired attire, Ninja Riot embodies ninja agility and precision. His initial quest for profit inadvertently ignites the central crisis, yet his eventual cooperation with former enemies underscores a capacity for change, framing his journey from self-serving antagonist to redeemed collaborator.