Dark Samus vs Serpent
Suggested by Sonic Dark Samus is a very well known Metroid villain in part because she is one of the strongest to ever show up. Her abilities are absolutely massive so even Serpent will have a bit of a tough time here. Still, he does have the advantage in strength as well as speed which is hard to get around. Her regeneration won’t be enough to endure these attacks. Serpent wins.