I would argue that the Plutonian wins this fight, due to his insane versatility.
Some aspects of his power set might be only theoretic though, like him being able to increase his own molecular density to make himself stronger and more durable, while at the same time decreasing the density of his opponents to make them more susceptible to his own damage. So in theory he could amp himself up and depower WB Hulk to levels, where he would be able to trade blows with him.
Plutonian also tanked multiple attacks, which were amped up by the energy of star-systems and he was still alive after that ass whooping. So I hardly doubt that Hulk's first punch would finish him off.
Plutonian can turn intangible, let mountains explode with a snip of his fingers and even more crazy stuff like that.
At the same time Plutonian has a clear speed advantage, since he was operating in pico-seconds or something crazy like that. He is much faster than the speed of light.
ON TOP OF THAT Plutonian might even be stronger than WB Hulk, since Plutonian was still standing while the weight of a solar system was dropped on him. Other powerful creatures, which were able to split planets in half with strikes and had the strength to deal with insanely high gravity settings turned into liquid, when they had to deal with the same weight.
I think that he is on another level than WB Hulk. Not saying that Plutonian would stomp, but he does have more advantages.
Plutonian before he discovered just how hax and broken his powers truly were made a gigantic diamond construct and used it to push an entire country underwater iirc.(Might have been a city, but I believe it was a country).
IIRC, it takes the equivalent of a supernova to hurt the Plutonian. Which is why his insane girlfriend was destroying an unknown number of star systems to harness the power necessary to beat the crap out of him.
There is no way in hell that Hulk is winning this fight.