Nyarth, called Meowth in English-language media, is a bipedal feline Pokémon who taught himself human speech and upright walking to impress a female Meowth named Meowzie. Abandoned as a kitten, he joined a Meowth street gang in Hollywood led by a Persian. After Meowzie spurned his human-like traits, he joined Team Rocket, inspired by the first human word he understood: "rocket."

As a Team Rocket core member, Nyarth strategizes and translates, devising schemes to snatch Ash’s Pikachu. His self-taught abilities drained the energy needed for his species’ Pay Day move, hampering his battle prowess. Yet he compensates with gadget-building ingenuity in non-combat crises.

Nyarth’s rivalry with Pikachu features reluctant alliances, like when a restraint forced them to collaborate against a territorial Rhydon. During their ordeal, he shared food and pondered their combative relationship, hinting at possible camaraderie beneath the conflict.

His loyalty to teammates Jessie and James clashes with his craving for approval from Giovanni, whose Persian he resents. Driven by a history of seeking validation—from Meowzie’s rejection to ambitions of becoming Giovanni’s “top cat”—Nyarth crafts elaborate plots, though overconfidence often foils his plans.

Occasional introspection reveals Nyarth’s depth: moonlit regrets, empathy for abandoned Pokémon. These glimpses contrast his usual mischief. He retains independence as a wild Pokémon, spurning Poké Balls, yet stays with Team Rocket through shared goals and camaraderie.

In spin-offs like winter OVAs, Nyarth navigates comedic roles—orchestrating a snowman Snorlax caper or retrieving stolen gifts—showcasing adaptability beyond villainy, blending humor with fleeting depth.