>>46124236And everyone remembers just how much Charizard sucked ass in gen 1. First two gyms are hell, you waste a ton of PP on Rock-types, and you get worn down all the time since you have neither the defensiveness of Blastoise, who also gets Ice moves and Surf while Charizard is stuck with Ember (no, seriously) until level 46 beating Blane. Nor does it has any move that lets it mulch through neutral targets effortless like Venusaur's Razor Leaf crit cheese (along with having significantly higher Special). Slash is pretty good, but it doesn't stand up to what is essentially a 165 BP move coming off of 100 Special vs 140 from 84 Atk. Yellow did fix this up a bit by giving it Fly but it also gave trainers a ton of weird jank movesets which really threw me off after playing RB. I know some people think Yellow is easier than Red and Blue, but I don't respect opinions belonging to the psychologically insane.
Personally, I didn't do one-mon runs, even as a child. I don't know how common it was back then for anyone to play the game using only their starter.