The question seems to assume that the goal of coaching and training are rescue; that the team is in trouble or incapable of success. That's horsefeathers.
I think that the more valid question is "are we working as well as we can?"
Here are my criteria for teams that don't need anything:
- We deliver
- Delivering software keeps getting easier
- We are always learning
- We have fun
If all four of those are true for a team, then that team probably doesn't need help. Of course if those are true, then the team is poised to provide a lot of help to other teams by describing how they work.