Bizarro flies at Unearthly levels.
The Legion of Doom * the inhabitants of "Bizarro's World."
Plotting to defeat Superman with a super-powered duplicate, criminal mastermind Lex Luthor reconstructed the Duplicator Ray invented by one Professor Dalton, who had used the machine many years before to briefly create an imperfect duplicate of Superboy.
Luring Superman in front of the ray, Luthor created an imperfect duplicate, which roughly resembled the Man of Steel and possessed all of his powers but, unfortunately, shared none of Superman's mental capacity. Composed of lifeless matter, this duplicate also shared Superman's memory, but in a distorted manner. Luthor dubbed this pathetic creature Bizarro.
Not understanding his Frankenstein-like appearance, Bizarro searched the world for acceptance, falling in love with Superman's girlfriend, Lois Lane, in the process. Appreciating Bizarro's plight, but not wanting to encourage his affection, Lois shrewdly used the Duplicator Ray to create an imperfect duplicate of herself.
Bizarro and Bizarro-Lois ultimately left Earth in search of their destiny and soon founded the Bizarro World in another part of the galaxy. Later, Superman reshaped Bizarro's world into a cubed configuration, making the planet as imperfect as its inhabitants. Today, Bizarro rules that planet, happy in the company of his family and friends.
It should also be noted that Bizarro's imperfect super-memory has given him a strange outlook on reality, and a perverse sense of warped logic, so that he seems to think somewhat in reverse. His speech pattern is ungrammatical, almost child-like.
If his mind worked normally, Bizarro would be a highly skilled combatant, Superman's equal. Instead, he is an incompetent, clumsy fighter, which is right in keeping with his character. It is only his awesome array of super-powers which makes him a real threat.
Bizarro's only known weakness is imperfect Blue Kryptonite, created by that same Duplicator Ray, which affects him exactly as Green Kryptonite affects Superman.