All of the above and:
Empathy – see the other point of view. You may not agree with it but you have to acknowledge its validity for the other person.
Be a good listener – you can not only read between the lines but also hear the true meaning under the words. Active listening is a skill that can be acquired through practice.
I would agree with your four choices, for sure. I would also add these:
They should have great body awareness. It seems obvious, but it’s never talked about. Unfortunately, I see so many trainers or fitness instructors who have poor form and little attention to detail or who just aren’t very athletic or coordinated.
Also, a great trainer will tailor the regimen to what each individual client needs, including different ways of communicating with each of them. Every single client is different. So while a tough approach might work well with a type A client, for example, more gentle encouragement may work better for others.