Team Rocket (Jessie, James and Meowth)

The trio debuts raiding the Viridian City Pokémon Center to steal rare Pokémon. Pikachu takes them down with a shock, and they decide to catch it as a gift for their boss, Giovanni. They become an almost daily fixture on Ash's road: they show up reciting "Prepare for trouble! And make it double!", set up disguises and pitfalls, and end up exploding into the sky yelling "Team Rocket's blasting off again!"

Jessie has an Ekans that evolves into Arbok, and James a Koffing that evolves into Weezing. Meowth is the rarest case: he taught himself to walk on two legs and speak human language to impress a female Meowth named Meowzie. She called him a freak, and he ended up in Team Rocket. He's wildly jealous of the Persian that sits in Giovanni's lap.

James, meanwhile, comes from a rich family. He ran away to escape his parents and an arranged fiancée, Jessebelle, leaving behind his pet Growlithe, Growlie. He collects bottle caps, keeps getting his head chomped by his own Victreebel and is, of the three, the one who truly loves Pokémon.

Early in Hoenn, the trio finds a poacher in Petalburg Woods who has captured a herd of Ekans and Koffing. Jessie and James free the Pokémon and, heartbroken, tell Arbok and Weezing to stay and protect the young ones. They move on with new Pokémon, like Jessie's Seviper and James's Cacnea, which loves hugging its Trainer, spikes and all.

In Unova, Giovanni promotes the trio. They swap the white uniforms for black ones and turn serious, with specific missions and no motto. During one job, Meowth gets fired and abandoned by his partners, but it was all an act to fool Ash. When the bigger plans in Unova fall apart, Giovanni pulls Team Rocket out of the region and brings everyone back to Kanto, and the trio goes back to its bumbling ways.

In Alola, a wild Bewear carries Jessie and James off to its den in the middle of a battle, and Meowth follows. From then on, Bewear looks after the three of them with food and shelter and appears out of nowhere to drag them away whenever a plan fails. Jessie now has a Mimikyu, which hates Pikachu more than anyone.

In the final stretch, the trio works out of Vermilion City and keeps chasing Pikachu, now with the world champion in their sights. After yet another failure, the three decide it's time to go their separate ways and say goodbye. It doesn't last: in the final episode they reunite and decide to go back to hunting Pikachu, as always.

In Japan, Jessie and James are Musashi and Kojirō, named after two legendary swordsmen, Miyamoto Musashi and Sasaki Kojirō. In English they became Jessie and James, a nod to the American outlaw Jesse James. In the games, Team Rocket is a group of nameless grunts; the trio was created for the anime and only later got a role in games like Pokémon Yellow.