IMO, Pedro was known more for his changeup than fastball. Maybe add Ryan or even Aroldis Chapman. I think Pedro's changeup was far greater than Hamels. The thing about Pedro was that he was throwing 95-97 mph on his fastball then drop down to about 78 mph on his change...it was pretty devastating. If you wanted to add a splitter you could name David Cone, Mike Scott, or Roger Clemens.
I think I just went with Pedro because he did have a great changeup, but it seemed to me at least that his fastball was his strikeout pitch, since he could throw it 97 MPH. Good points though. The reason I say Hamels is that he has gone whole innings, games even alternating between fastball and changeup. I like the suggestions though. Will be added shortly.