Can we cut out this contemptible argument please?
And just to make things clear- in absolutely no way, shape or form does wikipedia come close to being an acceptable source. Any one of us could post up there that Nihilus is a giant turnip being with fourteen mushroom heads tomorrow. It does not matter if it is the only source- it isn't a source at all. And if you say it is the same as another source, then use that souce, not wiki. Wiki will never, ever be a source- not in academia, and not here.
1. Traya vs. Sidious.
Personally? I think that Traya could theoretically just wave her hand and kill him with her instakill (DE Sidious is a different story). And if not, she could give him a hell of a fight until someone comes in to change the tide.
2. Nihilius vs. Dooku.
Dooku > Nihilius in combat ability, but Nihilius has his nifty Force drain. So Dooku goes down, one way or another. If the drain itself doesn't kill him, Nihilius will then strip him of the Force and cut Dooku down.
3. Sion vs. Anakin
Another case of "the PT combatant possesses better skills, but lacks that one nifty ability". That one nifty ability - invincibility. Sion and Anakin would fight for a long time, simply because - though Sion can't die - I see Anakin as his superior. Thus, Anakin will eventually be overwhelmed or Nihilius comes over and helps spank his ass.
Then, if Sidious isn't dead, they all WTFpwn him.