There’s a guy on Youtube named JRose11 who is on a quest to beat Pokemon Red with all 151 of the original Pokemon individually. He’s about 100 Pokemon in at this point. He doesn’t use crazy speedrunning tactics (he wants to approximate a normal-ish playthrough) but because he knows exactly where to go, what to do and what’s skippable almost all of his runs are under 10 hours (many are under 6 and he did it with Mewtwo in just under 2).