They're not really cursed, its just a birth defect(or something close to that), instead of having orange-red-like flames, Golbez has purple and indigo-like flames, works the same as any other Charizard's flames, though people have rumored and said that if you are touched by Golbez's flames, you be destroyed body and soul, though those are only rumors, nothing more. He has been given the nickname by all, Golbez of the Cursed Flames and yes he's one of my pokemon in-game as well.

Golbez the Charizard©to me

Charizard©to Nintendo/Gamefreak