Jessie and James are the lifeblood of the Pokemon anime. Ash's various companions have come and gone, but Team Rocket has remained resolute. Pikachu makes for a good mascot, and Ash is an effective everyman, but the essence of drama is conflict, and Team Rocket provides that brilliantly. When our own Eric Switzer watched every Pokemon movie in an attempt to review each one weekly, he discovered that movies where Team Rocket impacts the plot were invariably better than movies where they just showed up, or were hardly present at all.
Since Team Rocket are a trio (the infectiously charismatic Meowth joining Jessie and James), it might be strange that I'm highlighting Jessie alone. There are a few reasons for this. Firstly, we at TheGamer have singled out both James and Meowth previously for their greatness, and it simply will not stand that Jessie is yet to get the treatment. But also, Jessie is the de facto leader of the trio, it is she who comes up with the schemes, she who drives them forward, and she whose lenience gives James and Meowth the opportunity to lean away from the villainous nature of the organisation whose uniform they wear.
Jessie is Team Rocket. She might not run the whole organisation at the level Giovanni does, and indeed in terms of their overall global domination ambitions, she seems quite incompetent. She is constantly wasting her time trying to steal what amounts to an above average but largely unremarkable Pikachu. These creatures are not rare, and Pikachu isn't even shiny - although Pika's shiny is so garbage one could hardly tell.
The reason the trio remain in pursuit of Pikachu is because of Jessie's determination, but this is not some deranged Moby Dick obsession. It is very clear that she quickly grows fond of Pikachu and 'the twerp' and knows her presence pushes him to be better. She enjoys the one on one challenge of it all, but she is aware that her role in all of this is to push Ash forward. We see this in sport frequently - there can be no greatness without a second best. Would Messi and Ronaldo have carved out the same myths were they not constantly matching the other step for step? Would Liverpool be staring down the barrel of a quadruple without Man City constantly reminding them to give no quarter? They are Prost Vs Senna, McEnroe Vs Borg, Fischer Vs Spassky (or Harmon Vs Borgov). Jessie is essentially Ash's long suffering coach. She makes sure gym leaders remember, forever, the night they faced Ash.
She also had an incredibly hard life that her haughty exterior hides well. When she was young, she was so poor she had to eat snow due to lack of food. She harboured ambitions of being a nurse, but could not afford medical school, and so had to teach herself by studying Chansey. When this didn't pan out, she found herself in a motorcycle gang, and there is an implied history of frequent mistreatment by several of her partners. Jessie has spent her whole life searching for a place to belong, and that led her to the criminal organisation Team Rocket. She found herself ill-suited to criminal life but has found a way to survive by constantly failing just enough that she gets to continue supporting and sabotaging Ash's journey in equal measure. In doing so, she allows James and Meowth, who are outwardly much softer, to also keep up their charade, rather than being found out as kindly buffoons who have no place in Team Rocket.
Jessie is also an incredibly accomplished Performer, meaning she trains Pokemon for dance and other artist pursuits, then takes to the stage with them. The anime gives her arc a considerable amount of depth here, and also avoids cartoonishly making her blow up in a fit of rage afterwards. That's because when she fails at other things, she must overreact to keep up the ruse. With her Performing, she is free to be herself. Finally, she is free to be herself.
Pokemon simply does not work without Team Rocket, and Team Rocket (at least in the small, personalised way we know them) does not work without Jessie. Ash needs her, Pokemon needs her, we need her. Now, if only a game would let me play as her...