Nyarth, localized as Meowth, remains a constant member of Team Rocket alongside Jessie and James throughout the Unova journey. The character persistently engages in schemes to capture Ash's Pikachu or other valuable Pokémon, steadfastly continuing the trio's mission despite consistent failures.

During the Rival Destinies season, Nyarth collaborates in tactical operations, including manipulating Ash's Scraggy to incite disobedience and create capture opportunities. The character's interactions with Meloetta vary across media: the main anime depicts strictly mission-focused efforts to exploit its powers, while the Pikachu shorts portray romantic infatuation with the Mythical Pokémon.

In the Unova League arc, Nyarth contributes to a mechanized theft attempt, utilizing a specialized robot to abduct Pikachu at Professor Juniper's laboratory, though this intervention is thwarted. The character later participates in Team Rocket's temporary alliance with Team Plasma during the Decolore Islands journey, supporting coordinated efforts to locate and secure powerful legendary Pokémon before the groups separate.

Nyarth consistently uses speech patterns in Japanese featuring the verbal tic "nya" at sentence endings. While incapable of human speech illusions like other Zoroark or Zorua, the character relies on technological translations for complex communication during missions.