metahuman strength, speed, endurance, and reflexes, megamorphic power allows him to assume any human form, grow to tremendous size, or reshape his body composition at will, discharge concussive plasma blasts, teleportation, absorb outside sources of power to increase his own abilites, techno-organic virus allows him to regenerate from a single drop of blood if necessary
Though his first traditional appearance was in the pages of X-Factor, retcons since that time have identified the unnamed benefactor of the Living Monolith from Marvel Graphic Novel #17 as Apocalypse in disguise. Apocalypse's true name was revealed in Cable (1st series) #5.
The full scope of Apocalypse's powers has not been revealed. His mutation originally entailed great strength, megamorphic power to increase his size and mass, longevity, and energy discharges. Later exposure to a techno-organic virus at the hands of Cable(Cable / Deadpool #26) and Mister Sinister(Cable Annual 1999) made Apocalypse even stronger. In X-Men (2nd series) #97, he siphoned off power from the Twelve and assumed Cyclops as his host body. In this new form he could potentially summon all the mutant energies of the 12, and drain additional bio-energies to empower himself even further. His death in X-Men: Search for Cyclops #4 and rebirth in Cable / Deadpool #28 restored him to his earlier form and abilities.