The only pitcher I’ve ever heard of who was successful on basically one pitch was Mariano Rivera. Mo threw the cutter almost exclusively.
Have you ever heard of the knuckleball?
Wilbur Wood, Phil Niekro, Hoyt Wilhelm, Charlie Hough, Tim Wakefield, RA Dickey, Steven Wright?
There are actually a bunch of them in the HoF. They don’t get as much of a chance because of the way scouts are impressed only withy raw velocity nowadays, which is a shame.
Freegards