Re: Valkoriate vs. Sheev
Sheev is canon Palpatine who probably loses. Assuming Legends:
Originally posted by The_Tempest
Round one:With both characters at their peak, who would win in a 1v1 battle? Assume the contest takes place in the empty Geonosian arena as depicted in Episode II, a neutral environment.
Palpatine crushes him. If the two are comparable, or if Valky is marginally superior in the Force, Vitiate won't be able to kill Palpatine before he forces a melee, and then Valkorion obviously gets sliced and diced. His only hope of victory is to win really, really quickly, and that's only possible if he substantially outclasses Palpatine in the Force.
He doesn't, though; the reverse is closer to being true. Palpatine outmatches his greatest destructive feat (Force storms are more destructive than Ziost, and done without prep, a ritual or nexus), exceeds him in telepathy (dominating Luke and Vader >> not being able to dominate Scourge or the Outlander), exceeds him in telekinesis (muses that he can destroy the kilometers long imperial palace, is far more powerful than Vader+Starkiller, both of which have feats on the level of manipulating and destroying capital ships vs. destroying a random temple on a nexus), exceeds him in Force lightning (overloading Yoda's tutanimus >>> killing Darth Marr and random weaklings) and vastly exceeds him in Force speed (blitzing three celebrated Jedi masters + pre-vaapad Windu). Valkorion's only potential advantages come with rituals and sorcery that are useless in a one vs. one confrontation.
Sidious is also a more experienced and capable combatant, having trained with Plagueis by fighting and deflecting fire from hundreds of battle droids decades before his prime, while the Revan novel shows us how awful in actual confrontations Valkorion is whenever he actually has to fight someone.
Sidious is more powerful in the Force, and even if he weren't, he'd still win by virtue of being much faster and deadlier.
Round two:As a separate issue, which character is more cosmologically powerful? Your considerations should include applications of the Force in terms of both scale and skill, direct and indirect, destructive and passive. tl;dr: consider might and mastery.
Palpatine, and it's only marginally closer than round 1.
Destruction: Palpatine's Force storms threatened to "consume all of space". Even if you dismiss that quote as outlandish, they still demonstrate a far greater destructive ability than anything Vitiate has ever done, and can be performed without a ritual or nexus.
Telepathy (large scale): Valkorion does have impressive feats in this category, but once again, most of them are done on a nexus or via rituals, and Palpatine matches them with Byss. Palpatine needs neither to remove a specific memory from the minds of trillions of witnesses. He also manages to shroud the Force abilities of the Jedi Order at its peak, to the point where it couldn't detect him sitting right under its nose.
Telepathy (individual): Palpatine can mind fugg Vader from across the galaxy and force DE Luke to forget his name and become his apprentice, although the latter did happen on a DS nexus. Valkorion can mind fugg mando wars Revan and a few featless Sith and Jedi with prep and a dark side nexus, but he cannot do so to the Outlander.
Foresight: Palpatine is able to foresee and concoct elaborate plans throughout both the PT and OT, outmaneuver the most powerful Jedi Order in history, divine Anakin's fears and premonitions, etc. Valkorion was tricked by Revan into fearing a ravaged Republic with no army and virtually no Jedi Order.
Combat: see above. It's Palpatine and it's not even close.
Sorcery and rituals: This is typically Valkorion's strong suit, and he can point to Nathema, Ziost and some other impressive demonstrations of his abilities. Granted, Sidious didn't have several thousand gullible sith lords to work with, but it is still a point in Valkorion's favor. Palpatine strikes back with his cloaking himself from and shrouding the minds of the entire Jedi Order, and possibly the most impressive application in the mythos, wrestling with the Force and knocking it out of balance with the aid of Plagueis. He also claims in the Plagueis novel to also be able to manipulate midichlorians like his master, although apparently not to the same extent. Vitiate does have his galaxy-consuming ritual that would probably be the most impressive feat in all of Star Wars, but he never actually does it, so I'm going to remain skeptical. I'd say that they've shown different strengths in this category, although most of Vitiate's come from having the opportunity and more Sith to take advantage of, whereas Palpatine's are done under more or less his own exertion.
Immortality: Vitiate has a longer natural lifespan, although he accomplished this due to having lots of Sith lackeys that Sidious lacked. He is also more powerful in his spirit form, and can exist and act in multiple places at once, which Sidious can't. He might have an advantage here, but thanks to rituals that require large concentrations of gullible Force users.
Round three:Which character is more important? Consider the depth and scope of their geopolitical, historical, and cosmological achievements.
Just through tabulating the number of people they affected, it's probably Valkorion, given that he ruled around a quarter of the galaxy for 1300 years and then affects the entire galaxy for like 100. Palpatine's Empire was far more massive, but existed for a fraction of the time, and Valkorion having lived longer ago benefits from this metric through butterfly effects on progeny, etc. If we look from the perspective of, say, 1000 years after ANH, Palpatine would have probably exceeded him.
In terms of impact on the Force, it's clearly Palpatine, given that he knocks it off-balance and forces the creation of the Skywalker family line.
In terms of political impact, Palpatine overthrew a Galactic Republic and Jedi Order that had existed more less continuously for 25,000 years. Valkorion failed.
In terms of impressiveness, taking that leap from controlling a quarter-half of the galaxy to controlling all of it and exterminating the Jedi Order is far more impressive than tricking some Sith Lords and then hiding in the outer rim for 1300 years before waging war and failing. And Palpatine does this all in a fraction of the time and with a fraction of the help, against far more powerful enemies including the creation of the Force itself and his progeny.