Most people wouldn't considered Joker a genius.
But when you REALLY think about.. Joker is smarter than you realize.. WAY smarter.
The thing about the Joker is that he doesn't see his acts as bad OR as good.. he convinces himself, he is the only sane person in the world, perhaps with the exception of the bat. It is everyone else who hides their true selves under false masks of humanity, and make-believe tales of such delusonal ideas as love, kindness, law, and order. His whole existence is an attempt to strip these delusions away and reveal people for the selfish, depraved, chaotic clowns that they are. That is why he wears his clown makeup, because it reveals his true self far greater than the human face beneath, and why he then cuts his own face off entirely.
He is scary. Other villains want nothing to do with him. His methods and rationale are inscrutable. He only cares about Batman and only so far as it pertains to himself. Joker doesn't particularly care about other heroes, though they might entertain him for a bit. He is not a supervillain, he is Batman's disease. A curse on Gotham. A cancer. The guy who might just turn Batman into DC Comics`s greatest supervillain if his plan ever works. By virtue of this alone he is one of the most dangerous individuals on earth.
But the reason that the Joker is so distracted and obsessed with the batman is that here is a man who has also revealed the true dark side of humankind, and runs around at night wearing a terrifying bat mask to beat people into a bloody pulp. Yet somehow, despite the batman showing everyone that his true face isn't his human face, but the brutal, bloody, bat face, he manages to restrain himself from killing everyone and dancing among the corpses. Joker doesn't understand how this is possible and so becomes obsessed with this riddle, trying to solve it by pushing batman just that little bit further, to snap his restraints, so he can become as free and sane as the Joker himself.
Let's consider his actions. Johan Leibert is like Joker. He enjoys setting things in motion. He plays one person against another and then watches to see what happens. He gives people permission to live out their darkest fantasies, and then backs them into a corner where they have no other choice. Even other serial killers and regular people alike soon become caught up in Johan’s way of thinking and will do anything for him, or because of him.
He is a Monster. A true, bona fide monster cloaked in human skin. Simply put, a mystery. He walks around calmly in the shadows, killing with emotional detachment. He is incredibly charismatic, able to manipulate the toughs of the people easily and force them to do his bidding, usually killing the people he wants dead. He is able to exploit any weakness and use them to his advantage.He is the monster with no name. Johann is the pinnacle of Evil. He not only kills you, he makes you feel absolute fear by the time he's done with you.He with his brains, charisma and by being what he is can achieve what no other villain can without superpowers!