Board Thread:General Discussion v2.0/@comment-26347196-20151109173852/@comment-32948273-20160106130528

Aicilespear wrote: I don't know.

Omega Flowey does adhere to some chaotic patterns, but then from my experience, Flowey's damage certainly cannot match up to Sans. Furthermore, the pattern was easy to understand and dodge.

As you attack Sans, the difficulty inceases as you are no longer safe in the menu bar.There are little room for errors. Some of San's attack patterns can caught you off guard, and one hit of him is straight up brutal.

Funny enough, in the Pacifist route, Flowey was able to consume Sans's soul (Without his retaliation, at the very least). So I think, plot-wise, Flowey may be stronger than Sans?

But if I want to deny this fact, I can think of a theory that Sans's power is too evil and merciless, he had to hide it away for sake of Frisk's purity (considering Frisk is taking a Pacifist route) It's not linear like that.

Sans' raw power is extremely weak, he just has the ability to defy the laws of reality (the game) and make all your powers useless by doing stuff like negating your post-hit invincibility and so on. See here.

Anyway he's definetely the hardest by a landslide.