Re: Ultimate battle
Nice to see people know there are FAR stronger characters out there then the main known animes, aka DBZ. Having a form of immortality and reality warping are dangerous skills. The only people that could beat this person is someone who can do it better. Basically a higher being. I haven't read this particular manga so I'm not sure the extent of this person's powers. I could name a couple characters but I really wouldn't be sure if they could beat that person. I do know one that would always win or at least tie to any known fictional character.
This person is the main protagonist in Tenchi Muyo. He is a god. Basically any power you can think of, he can do with a thought. He can destroy universes with a thought if he wants to.
There are also characters from Slayers, Bastard!, and Saint Seiya that are also insanely strong as well with just as much power too. If you want to include other works of fiction like comics, there are a bunch of characters there that can probably win also. The One Above All, The Presence, The Man of Miracles are all equivalent to Kami Tenchi. There are also many who are close to this kind of power in comics as well, like Solar the Man of Atom. A non canon source that is pretty strong would be the Archie comics. This is the comics for Sonic the Hedgehog. Sonic and Shadow are pretty much invincible and can control time itself with the chaos force. They have beaten opponents who could crush multiverses with their hands. (A multiverse is many universes, kinda like how there are many galaxies in a universe.)
Hope that was a good enough answer.
Edit: or are you talking about who would win in that manga. The protagonist always wins so....