Is Darth Skotia stronger than Vader?
In the Marvel comics, Vader's suit is shut down by Cylo. After this happens, Vader is completely unable to move until he musters the strength in the Force to move his body. It took him some time to be able to do this, which implies that he was not strong enough to move his body with the Force until he shed his past identity completely and found the strength necessary to perform the task.
Darth Skotia was able to do the same thing when his body was shut down. However, he was able to maintain a heated battle with an early act I Nox. While we don't know how evenly matched they were (or if it was one-sided), it is still clear that he gave a hard fight, as was implied by Zash and game (can't be bothered to look for it, on mobile atm).
Next thing I'd like to examine is their cybernetics. After extensive research, I have estimated that Vader is at the very most 45-50% machine, where Skotia is repeatedly stated to be more than 50% machine.
TLDR: Skotia was able to move his body immediately, where it took Vader a while to be able to even stand up and activate his lightsaber. Skotia was able to contend with an early Act I Nox in this condition (immediately after losing his cybernetics), while Vader struggled to even stand. Vader's body is approximately 30-45% (50% at best) machine, where Skotia's is more than 50%.
Take that as you will