When he was still a normal street Meowth, the future Meowth of Team Rocket fell in love with Meowzie. However, she rejected him as her owner could buy her anything she wanted and Meowth, conversely, had nothing to offer. To try to win her love, Meowth tried to make himself more human by walking on two legs and learning how to talk in the human language, but she still rejected him on the grounds that he was now a freak Meowth.
Years later, after returning to Hollywood, Meowth met Meowzie again, now a member of his old Meowth street gang after she'd been abandoned by her Trainer. When the gang tried to force Meowth to rejoin them, Jessie and James drove them off with James's Weezing's Smog, and Meowth subsequently defeated the gang's Persian leader in battle. However, although Meowzie didn't want to join the gang, she told Meowth that she wouldn't feel right abandoning the Persian after he took her in, and admitted that she still didn't want to be with a freak Meowth despite all that he had done for her.
In A Hole Lotta Trouble, Max asked Meowth how it was possible that he could talk since he is a Pokémon. When Meowth started to tell his history, a flashback of him with Meowzie in the windows appeared.
She reappeared in Meowth's fantasy in Noodles! Roamin' Off!.
Meowzie was mentioned in JN072, where Meowth told Chloe about how he learned how to talk.