Saitama from One Punch Man takes on Omni-man from Invincible. If you didn’t know already, Saitama currently has no weaknesses and can not be harmed. His ability is to defeat anyone with one punch. He is the ultimate parody character placed in a real world in the Anime / Manga verse.
As far as Omni-man goes, he has a powerful healing factor and is invulnerable to any attack. He also possess super speed and strength. How powerful of an attack can he withstand? We really don’t know. But in this fan fight video by Anime Toons, we find out.