Meowth

Meowth is a member of the Team Rocket trio that are alwats following Ash, usually plotting to steal his Pikachu. His main difference from other Meowth, and pretty much any other Pokemon (besides Chatot), is that he can talk.

History
Meowth's earliest memory is being alone at Camp Pokéhearst. With no food, he was always starving, and tipped over a basket of baseballs believing it was food. As punishment for tipping the basket over, the baseball coach hung him from a tree; from this tree, he was able to see a movie called That Darn Meowth!, which depicted a Meowth in Hollywood being given delicious food by its family. Meowth instantly decided to go to Hollywood, which he believed would be a paradise.

However, when he arrived in Hollywood, he was merely a stray Pokémon, and was constantly being chased for stealing food. Soon, a Meowth gang, led by a Persian, took him in. Meowth lived on the streets as a member of the gang for a long time; the gang annoyed the humans in town, stealing food and causing trouble in general. One day, Meowth came across a female Meowth named Meowzie. She rejected him, saying that he was poor and that she preferred humans, so Meowth attempted to make himself more human-like to make her love him. Thus, he painstakingly taught himself tospeak 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.