Its the only way Nemesis would ever win. PH can't be killed. Sure he's slow, but he's relentless, right when you think its safe, he knocks your ass off a nearby roof. --- Fun Fact: I can play games with normal, inverted, and South Paw controls.
I dunno, i've been hit by Nemesis' rocket launcher and survived. But one single hit from the Great Knife and you're completely finished.
Sure, Nemesis can one-shot you if he picks you up, but IIRC, you have to be at fairly low health for that to insta-kill you. Pyramid Head can just flatout insta-kill you, no questions asked.
And he only died because he ended up killing HIMSELF. Or...themselves...or...whatever.
I dunno, I might just have to give this one to Pyramid Head. But logically, the fight couldn't happen anyway because in all reality, Pyramid Head is literally an imaginary friend. --- Yo Sephiroth, I'm really happy for you, and imma let you finish but Kefka Palazzo is the best Final Fantasy villain of all time.