My opener will be pretty short, since I prefer to prove a character's superiority by addressing opponent's points. Other than that, I believe Shimrra's superiority is so obvious, expanding isn't really needed - it would be like trying to provide analysis on why Palpatine > Vader. I will do that if others don't find Shimrra stomping on their own.
What I will focus in the beginning shall be the aspect of Shimrra's presumable tactics alongside his team. I strongly believe Shimrra would plan alongside the others for him to go for after the most warrior-type among the enemy. It's incredibly simple. Wyyrlok is the loremaster and an alchemist, the Force expert, Krayt is the balanced one, while Shimrra is the perfect Yuuzhan Vong specimen, warrior all-around. With Yuuzhan Vongs taking honor in a direct head-to-head combat, he will go after the one who seems to be able to give it. Among the three of the opponents it's obviously the armored, Djem So-wielding Ulic, not the robed Mace, nor youngster Galen. Ulic has the biggest warrior vibe, no doubt. I can easily go with Shimrra facing Galen, though. Against Mace - i doubt that, given ILS's post.
My basic point is - Shimrra can stomp either Ulic or Galen. Few seconds are all Shimrra needs to finish the fight.
Shimrra is an opponent on an entirely different level than all of his opponents. He's for all accounts and purpose Yoda level, or microscopically below him. None of the opponents can compare with him, that's all.
Galen Marek is basically Vader level. He is noted to be able to defeat him via exploiting knowledge about his fighting style, and basically having the best set of skills to counter Vader with said knowledge; greater mobility, greater agility. Now, this is the Vader below the version that RotJ Luke was an equal with.
Now Ulic Qel-Droma. How much of his power do you guys attribute to his education in the Dark Side? His best claim to power, equal fight with Exar Kun happened just shortly after his fall, without any real training in the dark arts. I guess the fact how absurdly Exar Kun is below Revan should do the math given amounts of powerscaling occuring later through the Banite line of Sith and their Jedi counterparts in PT time. Going to expand on this depending on the road you take, puting Qel-Droma as the weakest of your team despite how his "warrior aura" will definitely lure Shimrra, who can't sense how little power he has compared to others.
So, as I've said, Galen, who I believe to be superior to Ulic, is a combatant on pre-RotJ Vader, while we have RotJ Luke on par. Okay. And now let's go further. Shimmra fought Luke Skywalker by the end of TUF. That was a heavily tired Luke that just went through his whole citadel, and I know that, but it makes no difference. Even in this weakened state, Luke fought 15 Slayers alongside Jaina and Jacen, and managed to win, just before engaging Shimrra himself. And despite handling most of the Slayers, he... lost to Shimrra. Plain and simple.
I kind of really believe it makes everything over. We have Shimrra dispatching the tired Luke that stomped the Slayers, with Luke winning basically a'la Obi-Wan against Maul in TPM. Shimrra gloats, prolongs the execution, and Luke gets the time for a cheapshot. That's basically game over for me.
Nobody on the battlefield can hope to compete with Shimrra. At all. Shimrra was beating Luke who battled against four Slayers at once.
I can now provide dozens of quotes demonstrating Luke's skill development across the New Jedi Order era and how he is practically guaranteed to be reaching Palpatine levels, while Palpatine shits all over Kun and therefore Ulic. I don't have to do anything to demonstrate that also means shitting on Galen, since RotJ Luke already shat on superior version of Vader before achieving even enough skill to prevent being stomped by Lumiya. But I'll just go with the idea you guys know your stuff and won't be arguing the obvious. Happy to provide you with enlightenment if you don't.
You guys may try to argue "but Lightning", the only hope against Shimrra's laughable superiority. However, this line of thought really goes down the toilet. Luke used Emerald Lightning on a Slayer, oneshotting him, yet he didn't even try to do it against Shimrra. Too much pressure? Too little time? Too small distance? In any event, I really believe that Luke, after fighting Yuuzhan Vongs for 4 years, slaughtering them in thousands, really knows better when to use Force Lightning than we do. I'm kind of certain Luke, with all this experience against Yuuzhans and 30 years mastering the Force, really is wiser than JKBart or Ellimist in terms of knowing when it's the time to use the "trump card".
This is how Luke handled Slayer with Lightning, and still refrained from even trying to use it against Shimrra:
This might be because of the fact Force Lightning can be dodged. Luke and Shimrra, being levels above Slayers, Slayers being above Kyp Durron, Kyp Durron being dozens of magnitudes of power above Darth Bane, prime Darth Bane being superior to RoT Bane, prolly says that, when Hetton did this against Bane:
Given Hetton can dodge Lightning, I can't see how Shimrra can't do it against Galen's Lightning or any amulet power coming from Ulic.
That's it. The post is simple, basic as hell, because Shimrra's superiority is equally basic. I suspect a defense will be made, so here I am, waiting with about 50 books to quote, cause I really don't know where to start with stuff that's so obvious.