@Jayfournines: Molecule Man Destroys MJJ in less than half a second due to superior reality warping.
Molecule Man is not a reality warper though, and according to Marvel MJJ has a wider scope of power, where he can warp every aspect of reality, Molecule Man from what I understand has limitless power, but those powers are limited to a single aspect of reality. I for one don't think MJJ is a viable threat to the omniverse because he never showed he can do anything on that scale, but neither has MM. What molecules can he manipulate that MJJ can't? Considering they both have limitless power.