Superman considers the people of Metropolis his children and when you mess with his kids you'd wish you're dealing with the big blue boy scout. Plus, the man has dealt with Lex Luthor on a daily basis so a psychotic clown wouldn't even be in his weight class. It would be like dealing with a random criminal to him.
This also further supports my argument that he shouldn't be a Justice League level threat.
Flash: Would just speed blitz him and call it a day.
Martian Manhunter: Shapeshifting plus mind screw powers. On top with being just as strong as Superman
Wonder Woman: She has dealt with freaking Gods. GODS! It would be like taking out terrorist without breaking a sweat.
Green Arrow: Lets just say if this were Arrow seasons 1-2 version of Oliver Queen
Aquaman: Hope Mistah J likes to swim.
Even within the Batman mythos he works well as a Starter Villain that showcases just how fucked up the city actually is. Leaving him to his own devices just makes Batman look grossly incompetent as a hero.
Hell we've just seen that he wouldn't even survive a day if he ever crosses paths with Frank Castle
