If you're following the CG method, sulphates are a no-go. They are very drying to hair and strip it of moisture.
That being said, I use a regular shampoo every once in a while. For me, the bigget problem was silicone build up. So now I use silicone free stylers but still shampoo my hair every once in a while. I know it's not necessary but my scalp gets itchy and nothing makes it feel better than a good wash!