Thought this was interesting, it's a Sporcle quiz where players have 12 minutes to type down every gen 1 Pokemon.
I was looking at the results and, unsurprisingly, the most remembered are Pikachu, Charmander, Squirtle, and Bulbasuar.
Apparently the least remember gen 1 Pokemon is Exeggutor.
http://www.sporcle.com/games/g/pokemon/results 