Aw shucks, I feel like I'm going to regret this. But here goes nothing, because I honestly didn't have any motivation and energy to debate at all back then. But now, I feel better. So now I'm going to go ahead and straight up switch my vote to Inconclusive.
To be honest, Ness's real win condition here is relying on the Truth of The Universe, Which here it is assumed that Overlord has knowledge on its nature and abilities and even its existence within this battle (well mostly Overlord having knowledge of its existence but whatever). That's false, I don't see abilities or anything along those lines that will let Overlord detect or interfere the TOTU and it protecting Ness with fate. Even if Overlord has 2-C range (which it clearly says "Universal Level+", so someone might need to edit his profile a bit) with some of his jacked up abilities, I doubt it would be able to find Truth or let alone harm it.
Upon further inspection, Overlord has no resistance to Passive Fate and Probability Manipulation which pretty much makes this fight a bit less difficult that may result in Ness's favor or a stalemate via Fate. If GAIA's plan is to destroy the universe (or in this case, kill Ness or absorb him), Truth would most definitely make his abilities useless to ensure Ness doesn't lose and tip the scales to his favor. When I say "useless", I mean that TOTU could just make Overlord win con a 0%. This is all passive might I remind you.
