Humanity loses. Chara is genocidal and Arceus is kind of a dick.
As I said before, leaning towards stalemate/inconclusive. Conceptual beings are nothing new to Arceus, but Chara is extremely resilient once they've reached their absolute and taken the Player's SOUL, being unaffected by even True Resets and remaining in control. I also don't think Arceus could just unmake Chara in order to win, since it was the Player's DETERMINATION which brought them back from nonexistence, and now they're in full control of that. On the other hand, I don't think Chara is going to be able to seriously wound Arceus, and even if they could, Arceus has multiple ways to recover from it. Heck, even Palkia and Dialga showed the ability to bring back things that had been erased entirely, so Arceus logically should be able to do so, as well.
In conclusion, Llama God and MURDER_CHILD.exe probably just sit in a void for a while with Chara blasting Linkin Park.