What is the Superman challenge?
It's a series of three tests, to determine if a character is faster than a speeding bullet, more powerful than a locomotive, and capable of leaping tall buildings in a single bound.
To be more specific these are the challenges
1. A 9 milimeter handgun will be fired down a 1000 meter race track. The character must beat it to the finish line. The character cannot start moving until the bullet begins to move.
2. Take two fully stocked freight trains. One of them will be pulled by the character, while the other will be moving like a train normally does. The character must pull their train for as long as the regular train, at speed equal to or greater than the regular train
3. The character must jump over the Burj Kalifa in with a single jump. They cannot take a running start. Flying characters cannot use their flight for this, in must be a jump