Shapeshifting of course. Shapeshifting allows you to change even your genetic and cellular makeup to perfectly match that of whoever you're mimicking. That means, shapeshift into Superman, boom, flying, superstrength, x-ray vision, etc. However, the limit to it is if those powers are part of their genetic makeup and not an ability one has, ie. Superman's powers are given to him via sunlight, so with the same cellular and genetic structure that of Superman, you can use his powers. However, if it's something like Azazel who can teleport, you can look like him, but unfortunately can't use his power to teleport... :'(