This is a bit of a laymans guide to predicting the outcome of breeding morphs with co-dominant and dominant traits eg: Pastel Ball Python in this case, but could be a Lesser Platinum Ball or Leatherback Bearded Dragon or any other co-dominant or dominant morph.
The easiest way, is to draw a Punnett Square.
NN= Normal (wild morph)
Np= Pastel
pp= Super Pastel
Normal to Co-dominant
You can see you would get half Normal (NN) and half co-dominant pastels (Np).
Co-dominant to Co-dominant
Results in 25% Normals (NN), 50% Pastels (Np), 25% Super Pastels (pp)
Dominant to Normal
The result of breeding a normal to a Super Pastel (the dominant form of the co dom Pastel) You would get all Pastel's.
Dominant to Co-dominant
If you paired a Co-dom Pastel to a dominant Super Pastel, the result would be 50% Pastel's and 50% Super Pastel's.
Dominant to dominant

The result of a Super Pastel mating to Super Pastel would result all Super Pastels!
NOTE: All these Punnett Squares illustrate theoretical outcomes, but by no means guaranteed!