Pastel is just a name for a more brighter and colorfull animal.
Pastel does not have the dark sides in its tail, his side drawings are fading en surounded with more pink. And it's back has to be clean as well, there are a few pastel lines, but a pastel can be born from 2 normals either. Pastel is a polygenetic morph, this means it is nog sure how it breeds on, but will definatly improve youre morphs.
A few pastel lines;
kubsch (euro-pastel.)
dutch pastel
maron (tough they deleted the pastel part they called him maron pastel before, but still nothing is proved yet so i have to see..)
and some more lines,,,,
The greatest pastels come from selective breeding, and they are fun to breed because you can create whatever you want with it, and afterwards you can start to improve your morphs with it...