Sylux is a Blue suited Bounty Hunter from the Metroid Prime series and possible playable character in SSB4. Not much is known about it except it has a hatred towards Samus and the Galactic Federation.
Sylux is fitted with the Shock coil weapon which shoots a small, continuous beam of blue electricity. If this connects with the opponent, it slowly begins to drain the opponent's health, and as the beam is connected, the rate of the drainage will increase. If Sylux is the one using this weapon (which is not always the case since it is obtainable in the story and multiplayer mode) the drained health returns to Sylux, adding to its own.