X-Ray Moves are devastating (and more violent) combos that will showcase how much damage the moves does to the victim. To execute X-Ray Moves, you have to fill your character's SP Meter in the bottom then press L2+R2. X-Ray moves are unique per character and they don't seem to change even when players change variations. These are not really finishers as damaged opponents will brush off the otherwise devastating damage they suffered earlier.
X-Ray moves can be evaded or blocked. Successfully Blocking an X-ray move will fully drain the opponent's SP meter.