Meowth's tale is a sad one. He started life as an ordinary street Meowth, searching for food wherver he could find it. He even went to Hollywood in search of food, but found nothing. Desperate for food, he joined a gang of Meowths led by a Persian and stole food from shopkeepers. Then his life changed when he saw Meowsie, a female Meowth, in a shop window. Unfortunately for him, Meowsie was owned by a rich lady and thought she was too good for Meowth.
Meowth was heartbroken, but he was determined to impress Meowsie by walking and talking like her owner. During one of the gang's food raids, he attempted to run on two legs, but was caught by the shopkeeper. That did not stop him from trying to improve his skills, and after much practice, he was able to run on two legs. During that time, he learned how to read and write by listening in to ballet classes while the teacher taught the students to enunciate. He obtained a picture book and tried to match letters with pictures. The first letter he learned was "R" and there was an image of a rocket. Since Team Rocket's logo is an R, we now know the reason why Meowth joined them.
After learning to walk, talk and write, he went to Meowsie, but she instead of being impressed, she called him a freak! Meowth couldn't believe that all his efforts were in vain, and so he left Hollywood and became the brains of Team Rocket's operation (not counting their boss). His ambition is to become the boss' top cat, replacing the Persian he owns.
Years later, when Meowth returned to Hollywood for the premiere of a Pokemon movie (not Pokemon: The First Movie (aka Mewtwo Strikes Back) - now in theaters), he found out that Meowsie had joined Persian's gang after her owner abandoned her. Meowth tried to get Meowsie out of the gang and even got into a fight with Persian (and won!) to win her heart and freedom, but she remained loyal to the Persian because he took her in when she had nobody left in the world. So Meowth is once again with Team Rocket, searching the world for rare Pokemon, money and power....and love.