It was never shown in any episode since the Season 6 Premiere how Dark Laser even escaped from Unwish Island.
He has irritable bowel syndrome, as revealed in Wishology!
Dark Laser is a parody of Star Wars character Darth Vader. His character inspiration is due to the fact that Butch Hartman himself is a Star Wars fan, and that his character is an obvious parody of the iconic villain Darth Vader of the same franchise, as is the fictional franchise that Dark Laser is from, Space Wars. Many of Dark Laser's minions are also modeled after Star Wars droids and storm troopers.