In 2002, Randy Johnson threw 260 innings, and struck out 334 batters.
He threw a four seam fastball 54.9% of the time and his slider 41.9% of the time. The last 3 percent was a combination of changeups and splitters.
Maybe you don't consider throwing two pitches 97% of the time rather than 100 being a "two pitch pitcher" though. Who knows.