RBY Misty was pretty impressive as a gym leader imo. I mean, it's your second Gym, you've got a piddling team of NFE pokemon, and your strongest moves against her is a 40 base power vine whip (maybe).
On the other side, she busts out a fully evolved OU special sweeper with a STAB base 60 attack coming from one of the best offensive types in the game, water. FUCK (the RBY animation for bubblebeam was simply epic to match)
If you were like me and had a team of 6 13-14 pokemon with no ivysaur on your first run (or frankly, even with ivysaur), you were like, FUUUUUCK!!!
"Hmmm... a name for this plan..."