This doesn't go in the off topic section. Off topic is for threads that deal with non anime and manga discussions.
@Shadowchaos: Arguable. While Kami Tenchi is easily among one of the strongest characters in anime/ manga, his status as an omnipotent being was left vague in the OVA series and is thus questionable. The same thing would be said of Slayers' Lord of Nightmares, who has been thought by some to also be one of the few omnipotent beings in anime/ manga.
@Dream: I guess I could say U-DO from Xenosaga if you count video game feats and added it to his anime version. If not all you have are mind controlling over 600 people causing Albedo to go insane and then in a possible future when it met KOSMOS destroyed a galaxy or maybe might have been more it was unclear when their attacks met