I'm the captain of my team, and I'm certainly not the strongest player on the team. But I usually do the coaches for our SL2's and 3's, cuz I talk to them the right way, and don't ask them to do something they aren't capable of. And I start off by asking them what they were thinking about doing first...
For any of our mid level players, I'll coach or the other mid levels will coach, when we don't have our SL7 handy.
I rarely call a timeout on someone when they're down on the shot, but if they are obviously taking the wrong shot, I will, usually just the SL2's & 3's on our teams...
You do have to understand how your players will react, and bear that in mind before calling a timeout. I had a captain of my first team who was very strong minded about this, and wasn't sensitive to how players felt. We lost players as a result. It is supposed to be fun, and if you act like a dictator, well.... Know you're players.