I use superdrugs natuaral range coconut shampoo and intensive conditioner. My son is 2 and has short hair, and to be honest i dont wash it that often like once a month.
I use the same on my daughter who is four years old and i wash her hair every other week.
The shampoo is mild but moisterising and the intensive conditioner is very moisterising and mild it helps to comb out my daughter's hair so its easier to comb aftrewards.