Again, children's series. In Pokemon, the main characters are all about friendship and caring for Pokemon and being friends with them. Those are the heroes. Team Rocket only cares about stealing Pokemon to make money, gain power and take over the world. They don't care if people or Pokemon get hurt in the process. That is decisively against everything the heroes stand for. Therefor they are the villains of the series. That's how human cartoons work.
Text; Bad. :| Bad Vriska.
In Pokemon, the main characters are all about friendship and caring for Pokemon and being friends with them.
Those are the heroes.
Team Rocket only cares about stealing Pokemon to make money, gain power and take over the world.
They don't care if people or Pokemon get hurt in the process.
That is decisively against everything the heroes stand for.
Therefor they are the villains of the series.
That's how human cartoons work.