In this brilliant Spiffy Shorts parody, Superman faces off with Darth Vaders' Executor-led Star Destroyer fleet and ultimately against the Sith Lord himself. Watch it here:
The million-dollar question is, could the Empire realistically use Kryptonite to power lightsabers, blasters, and tie fighter fighter craft weaponry? I suppose the answer to an imaginary question pretty much has to be a qualified "maybe" or even "why not". If Kryptonite are bits of the exploded planet Krypton, there's no reason that ore, although not found natively on earth, couldn't be found anywhere else in the galaxy. Perhaps to the Empire, it's known as Crystal54, the same boring stuff that powers the holo-disc readers in every hotel room across the galaxy.
But let's pretend Darth Vader was caught in the bathroom without his lightsaber on him, would a grunting match a la 'Eastern Promises' on the tile floor with Superman end as easily? Hard to say. Superman is, of course, unfairly physically powerful, but then it's possible all Darth needs to do is use the force to tweak the vein leading Super-blood to the Super-brain and the red and blue crusader crumples into a pile of Super-vegetable. So maybe a lightsaber to the heart is the best way to go, after all?