Apocalypse is believed to be the first ever mutant born. Yes, the very first one. He is over 5,000 years old and grew up in Ancient Egypt, where he was given the name En Sabah Nur (The First One). Apocalypse's main mutant ability is molecular reconstruction. This means he can change his form as he sees fit, changing both appearance and physical traits including turning his limbs into blades or other natural weapons. He can even increase his physical size and attributes by psionically drawing on external (perhaps extra-dimensional) power sources. This makes his strength limitations practically incalculable. He has fended off entire teams of X-Men at once, and in an alternate reality had taken control of the world.
The Martian Manhunter possesses a wide variety of superhuman powers and abilities, which have been shown inconsistently throughout the years.
In the current DC continuity, many of his powers are similar to those of Superman, including super strength close to that of Superman (though as shown in the Death of Superman crossovers, he was no match for Doomsday), flight, invulnerability, super-breath, and "Martian vision" (a term designating both the ability to see through solid objects and the ability to project beams of energy from his eyes). Superman once said of the Manhunter, "He is the most powerful being on the face of the earth".
During the 1990s, it was stated that the source of his flight and "Martian vision" is a limited form of telekinesis (he had occasionally demonstrated more traditional uses of telekinesis to levitate and animate objects during his Detective Comics and House of Mystery appearances). His "Martian Vision" energy beams have sometimes been shown to knock foes backwards, which could (theoretically) be due to their telekinetic nature. On most occasions, however, these energy beams are depicted as heating objects rather than delivering a concussive impact.
The Martian Manhunter possesses the power of shapeshifting, which he employs for various effects (adopting human or monstrous appearance, elongating his limbs, growing to immense size, altering the chemical composition of his body, etc.).
J'onn can become intangible, passing harmlessly through solid objects. He can also render himself invisible.
He is a powerful telepath, capable of both perceiving the thoughts of others and of projecting his own thoughts. He often acts as a "switchboard" between minds in order to coordinate the Justice League's actions. The extent of his telepathic abilities is great; several times he has connected his mind to the entire population of Earth.
He has demonstrated regenerative abilities, once able to regenerate his entire body from only his severed head but with great strain (due to the loss of mass, he found it necessary to incorporate new matter from the Martian sand). Early appearances of the character show him as able to breathe underwater; the last time he displayed this power was when he encountered Zauriel in the sea of San Francisco in JLA #6. The Manhunter has sometimes been said to possess nine senses, but these additional senses are poorly-defined and generally ignored by most writers.
Aside from his superhuman powers, the Manhunter is also a skilled and very capable detective. As Batman mentions in his file, "in many ways, Martian Manhunter is like an amalgam of Superman and the Dark Knight himself."
http://en.wikipedia.org/wiki/Martian_Manhunter#Powers_and_abilities