An interesting match-up that I think would provide the Saiyan one hell of an opponent, the vicious Cybiote from Marvel Comics known as the Fury.
One of my favorite Marvel villains, this killing machine would give Goku a MAJOR run for his money. Particularly the version that faced off against the mad reality-warping mutant Jim Jaspers. The Fury was able to evolve and adapt to Jaspers's attacks, eventually computing a way to kill him by teleporting the two of them to the formless void between realities (space between spaces?
) therefore robbing the then-bewildered villain of anything to really warp... before swiftly frying his brain.
Though it WAS immensely weakened from the experience (traveling between realities takes a huge cost on the creature)... and thus the heroes of Earth-616 were able to defeat it upon it's return. Needless to say, when the Fury gets involved, things (USUALLY, depending on the writer) tend to get pretty dire for whoever's set against him.
Suffice to say, Goku would most likely get over his love of 'making it a fair fight' pretty damn quick if he wants to survive against something of this caliber. Would he be able to win? Probably, if this was an episode/issue of the Dragon Ball franchise he'd find some way to overcome... but elsewhere? Probably not so set in stone.
Just wanted to use my old Fury sprite edit again, so threw him/it against Goku. Why not? Dude's gone up against all manner of foes and fellow heroes from around the world of fiction... so why not the Fury?
Goku sprites from "Dragon Ball Z: Extreme Butoden" for the 3DS
Background from some random Dragon Ball game. (forget)