When James’s Mareanie learns a Dark-type move, Team Rocket realizes this could be their chance to put their Dark-type Z-Crystal to good use! The Boss sends them to Ula’ula Island to get a Z-Ring from the kahuna, who’s a former associate.
Meanwhile, at the library, Acerola tells the story of the Greedy Rapooh—who turns out to be a real Gengar with thieving tendencies, and who steals Team Rocket’s Z-Crystal and takes off with Acerola on its back! When Kahuna Nanu sees that Team Rocket is battling to rescue his young friend, he lends them a Z-Ring—and after the battle, Acerola gives them a special Z-Crystal for Mimikyu!