Have you ever wondered why your chicken pieces seem rubbery when you make a chicken curry?  Well The secret lies in  whether you use tomatoes in your curry or not.
If you are going to make a gravy/curry using tomatoes  , then use only thigh pieces of the chicken. The breast pieces usually tend to get stretchy when cooked in Tomato gravy.
If you plan to cook a chicken curry  using a whole chicken avoid using Tomato as your gravy base (or add tomatoes at the end)