Shampoo Vs. Soap: I do not use shampoo. It is simply too harsh for fragile pony hair. For ponies who REALLY need their hair to be washed, I use a gentle foaming hand cleanser. I really like the Anti-Bacterial Gentle Foaming Hand Soap from Bath and Body Works. I also consider liquid soap a little too harsh, so stick with foaming cleanser.
Conditioner: I prefer a cream conditioner with high moisturizing properties. Herbal Essences Hello Hydration and Garnier Fructis Fortifying Cream Conditioner for Dry or Damaged Hair are my favorites. I like to saturate pony hair in this conditioner and let it stand for a minute or two before rinsing.