THE icon of superheroes and one of the original costumed comic book characters. Baby Kal-El was one of the last surviving members of the planet Krypton, which died a horrible explosive death.
Due to his kryptonian physiology Superman's powers are fueled by Earth's yellow sun. Under the energy of a yellow sun, Supes has vast superhuman strength, near invulnerability, heat/x-ray vision, and the ability to fly at light-speed. He can also survive in space without the aid of a suit or breathing apparatus.
Superman does have three main weaknesses. The most commonly known one is kryptonite. That will kill him after prolonged exposure. He is also vulnerable to magic attacks and influence. While magic will not kill him in the context that kryptonite will, but it will harm him far more easily than conventional attacks. Last, but not least, exposure to energy from a red sun (the same sun Krypton was under) will deprive him of his powers and turn him into a normal scale human.
Although he is one of the longest running characters in the Marvel Universe, Iron Man is a "late bloomer" to mainstream popularity. Perhaps this is due to the two blockbuster films released in the last two years.
Tony Stark is a human with no real superpowers, but his incredibly scientific mind has enabled him to construct various armors.
For Slugfest purposes, Iron-Man is using his current "Bleeding Edge" Armor, which is nanotech based. It is comparable to many of his "classic" abilities (supersonic flight, vast strength, and various energy blasts) but can be literally housed inside Tony's body. It also has incredible self-repair abilities, able to repair itself in seconds.