I would have the ability of perfect control of time (cliche, i know). I could speed up ans slow down, reverse, fast forward, travel, as well as doing multiple of the above at once. My secondary power (im greedy) is precognation.
I would be weak to someone who proves me incompetent, because i hate it when i prove to be less than par or the best.
I would be called Know-All, because of precognation as well as having traveled to the future.
My evil would manifest as me almost killing anone who could or will be a threat to me. The almost vecaue that way it leaves an impression, and so it sends a message, that i dont wven need to kill to say in power.
My costume would be a v-neck with jeans, because i wouldnt need any costume to strike fear or win combat, becajse of my foreknowledge as well as insane abilities.