It all depends on if you consider TOAA to be an actual writer, or just part of the story. If it's the latter, he can't do anything against PM, and would just dissolve into non-existence once in direct contact with him.
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“Perhaps this is the ultimate freedom. The freedom to leave.”
How is he the deciding factor? It said that he was everything outside of what is considered Marvel. We don't even know what that is. Furthermore, TOAA and the PM are considered supreme. Which means that they have no equals. They are both the writers. Which means they are over everything in their respective "universes". Including the characters listed. This will be a battle between the two "gods". They others will not matter.
But if a character is introduced that comes from beyond the Marvel Universe he can in theory be more powerful, despite him still being technically a character created by Marvel. Because TOAA is still a character within Marvel.
If our God does exist for example and he was introduced into either Marvel or DC Universe he would obviously stomp everything at once including the real world.
TOAA could never affect the real world though only the Marvel Universe.
So why would anyone in this thread other than TOAA and PM matter? It's a stalmate, neither one has an edge. Not even if you back one side with all of their characters. The extras don't matter. Only the "god" of their respective universes. If beyonder was supreme, then it would be a three way tie, but being everything outside of somewhere doesn't make you as powerful as the maker of the object you surround. Threads like these are pointless because the scale is too immense and the characters too equally matched. So like I said, it's a stalemate dude.