Meowth

"Meowth, that's right!"

- Meowth's Catchpharse

History
Meowth is the brains of the Jessie/James/Meowth trio in the Pokémon anime. They have another Pokémon that is almost as important as Meowth: Wobbuffet. When he was younger, Meowth lived on the streets in Hollywood after he came there in search of fame and fortune. He was a member of a gang of street Meowth that was led by a Persian. This gang annoyed the humans in town, stealing food and causing trouble in general. One day, Meowth came across a female Meowth named Meowzie. Since she rejected him and preferred the company of her rich human mistress, Meowth attempted to make himself stand out from other Meowth and become more human-like to make himself "worthy" of her. Thus, he painstakingly taught himself to speak human language and walk upright like a human. When he approached her after this transformation, she once again rejected him, calling him a freak. Heartbroken, Meowth remembered the first human word he learned to speak - "rocket" - and was inspired to join Team Rocket.

In Go West, Young Meowth, Meowth, Jessie, and James returned to Hollywood while following Ash and Meowth was reunited with Meowzie, who had since been abandoned by her mistress and was forced to join the gang of street Meowth. Meowth fought his former Persian leader to win Meowzie's love, and won, but Meowzie demonstrated that her loyalty was with Persian since he took care of her when she needed it, and Meowth was once again heartbroken.

Because of the effort Meowth exerted while learning to speak and walk like a human, he has not learned the signature move of his species, Pay Day. In Meowth Rules, Meowth was worshiped by an island of people who believed that he could bring them riches with Pay Day. When he was caught in a battle meant to induce Pay Day, Jessie and James had to secretly bail him out by throwing the last of their spare change and some of James's prized bottlecaps in order to appease the islanders. Upon learning of its species's love for gathering coins and shiny objects from Ash's Pokédex later in Do I Hear a Ralts?, Jessie criticized him for not doing so.

In Meowth's Scrafty Tactics, Ash and his friends find him seemingly injured. He then claims that he messed up one of Team Rocket's plans, and that he was fired by his boss, and Jessie and James leave him. At this point, he had traveled with the gang for a while, even to the point where even Pikachu trusts him. However, in the episode Crisis from the Underground Up, it's revealed that his claim that he was fired from Team Rocket was false, and that it was a diabolical plan that was orchestrated by Jessie James, Dr Zager, and himself to capture all of the gang's Pokemon. He then escapes on a jetpack along with his comrades when the plan fails.

Trivia

 * When Meowth & Team Rocket started their adventures in Unova, they began to have serious personalities which later became a huge insult to many Pokemon fans. It is even notable that they don't have comedic roles anymore, focuses on missions instead of capturing random Pokemon that would "impress" Giovanni & when they blast off, they are seen wearing jetpacks retreating instead of blasting off in defeat. When the trio started their adventures in Kalos, they returned to their comedic personalities.
 * A lead suggestion to this is that rumors has it that the trio are the main reasons why Team Aqua, Team Magma & Team Galactic had minor roles in the anime, which could be the possible reason why Team Rocket was given a smaller, serious role in Best Wishes which was later given to Team Plasma.