system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] What if the Joker was good and Batman was a villain?

What would happen if the Joker was a Chaotic Good hero defending Gotham, and Batman was a Lawful Evil vigilante terrorising the city? How would this effect things like the Justice League?
gpt
That was partially adressed in Crisis on Two Earths where the Jester (Joker) worked alongside Luthor to stop Owlman (Batman) and the rest of the Crime Syndicate.

Batman would probably be more extreme in his methods and enhance himself and his allies with technology to get the edge, can see him using Venom extensively once he learns of it and using scare tactics to keep control of the mob.

Joker would try to stop him with gimicks but probably end up killed by the more ruthless Batman. He just doesn't have the resources or training of The Dark Knight (unless you also switch their families).