Here is a theory on how no single character has omnipotent dominance over all other character. I posted this before on a similar topic.
Well I can't really agree with anyone who claims any seen in the series character (not unseen) to be omnipotent. Because if their is someone who is omnipotent it sure as hell ain't anyone we seen. Kami Tenchi as I see it is only omnipotent in his verse the Tenchi-Verse (all forms of Tenchi Muyo included). If he were to fight the strongest of another verse like say Goku from the Dragon Ball series (end of GT Goku is possibly the strongest unfused character after training for 100 years after the end of the battle with Omega). For one we only know that any new version of Goku is stronger than his last seen since he always loves to train. And so it is highly likely he is stronger than in Z. However after we see him after 100 years we only know he got stronger. But we don't know how much because there is not a single piece of footage of him fighting. So he could range from a list like below.
1: Goku only got as strong as Omega in SS4.
2: Goku got as strong as Omega in base form.
3: Goku got as strong as Omega in base form at only 15% of his base maximum thus making it a cake walk for him to fight Omega.
4: Goku could nuke Galaxies (Final form of Cell could blow away a solar system as stated in the manga)
5: Goku could nuke a universe.
But when it comes to picking a fighter it is not useful to use end of GT Goku as we have no knowledge other than "He's stronger than before".
So I could say Getter Emperor. He was only planet sized but his energy began as an equal source to a big bang and quickly rose to beyond as he absorbed the infinite amount of the sentient energy known as Getter Rays and the planets thenselves (the infinite godly energy that powers the other Getter Robo's and is the very essence of evolution. It also exists within the planets. So when he finally absorbs his universe (most likely he will destroy his own universe) he will have the equivalent energy of two universes basically. And he is easily capable of manipulating space and time so he is highly likely able to enter into other dimensions. So unless they prevent him from being able to absorb planets and more energy he will continue to absorb universes until he is possibly able to star nom nom noming on a multiverse depending on it's size (he might even be able to produce infinite amounts of Getter Rays being the supreme emperor of all Getter Robos and therefore might even be master to the energy itself). There is also a noncanon version which is only noncanon in the fact that it was a part of an anthology book and therefore the feats it performed might be very likely to be capable of happening to the canon version as well. In the anthology book the emperor was fighting a god like being bigger than a galaxy similar to Kami Tenchi in size and all it took was a one hit kill from a simply punch to the head from the Emperor to smash it's head and even turn it's head into a galaxy from the way it just exploded and the way it formed into some kind of spiral (not the Spiral concepts from Gurren Lagann but a spiral) like thing. And after that we get a glimpse of the Emperor dwarfing the majority of the universe in size. So for this fight it would be hyper dimensional god vs universe devouring evolution god.
An omnipotent being can basically do whatever the fuck he wants, if he says that gravity is not gravity then it's not GRAVITY! That's just how it works with an omnipotent, anything he says goes... Or anything does is considered logic to his perspective. A human mind could never imagine how powerful an omnipotent being is because we aren't that smart enough to realize than an omnipotent being can do whatever the fuck he wants without no consequences. If Kami Tenchi has a limit to his omnipotent powers or consequences that follow him then he is not omnipotent, just nigh-omnipotent. The best example of an omnipotent being would be God from the Bible, One Above All, Man of Miracles. An omnipotent should be above anyone no matter how powerful they are unless they're of course another omnipotent.