Rappers have pitch and you can notate it. Most rappers have two different notes they use a semitone apart. Other rappers use more...especially older ones from the 80's.

Producers work with rapper's pitch all the time so their in tune with the song. Similar to tuning a drum set. Alot of rapper's just do it naturally.

You can notate all that stuff.

Edit....off the top of my head, check out 'Dopeman' by Ice cube. Lots of use of pitch there.

Obviously you got guys like Slick Rick who used pitch all the time. \