Avatar the Last Airbender is anti-fascist and also a great show all around.
However, I nominate Samurai Jack for best politics. Jack unites exploited peoples across the realm and even leads violent slave rebellions.
Bonus terrible answer: Pokemon, which is a capitalist hellscape fixated on slave-animal bloodsports.
I’m not into anime, but if you are then you should check out the one about Marx, from China.
https://www.youtube.com/watch?v=0T0a_jXHiDo
Lmao, they really made a baby Marx