If you were referring to a battle of the Force - I have no clue. It has been hinted that Sidious is so powerful in the Dark Side that it literally ravaged his entire body. That is the greatest explanation for his being deformed upon his battle with Mace Windu. It also seems that Sidious is strong enough to shield himself from the Jedi Order - all of them. A feat which Illustrious has told me only Exar Kun, Ulic's very own master, is capable of doing.
So it would appear to me it requires a lot of strength in the Dark Side. Ulic was a fallen Jedi, and did several villainous deeds under Exar's tutelage - but I want to say he was just strong with the overall Force. Not with the Dark side.
Um. I dunno. It sounds like I'm sticking up for Sidious -- which I am. But not because of any preferance or bias. Simply because I don't know a lot about Ulic.
Someone give me an estimation on how much power he possessed, without being biased?