The "standard" yorkshire should have a silky coat, like the name suggests, it should feel like silk, your fingers run through it easily, it does not matt often, and should be easy to work with. My friend has a s**tzu and her coat is way thicker than Mojo's. Maybe you can ask a friend or even some groomer that have experience with yorkies to help you decide if her coat is cottony or silky, it can also be a mix, it's kinda confusing..i know
But after your decide what type of coat she has it will be easier to treat.
My friend that completely shaved her yorkie say that after that the hair is thicker so it has more body to it. Still mats often but it is easier to work it out since it doesn't break as much, she just takes a lot of care to keep the coat moisturized at all times, it is also very important that you don't brush a dry and dirty coat.