Stal, any ride like that with multiple roles, a CM will be trained for all roles. I have not heard of any ride that is an exception (it would have to be a big ride.)
If you are trained on a ride you have to be able to pass a test for all parts of the ride. This is because attractions rotate CMs every 45 minutes or so depending on the ride. This prevents fatigue from working certain positions and helps to keep attractions people fresh. If a person is not approved in certain roles, it will mess up the rotation and that person will most likely end up "stuck" in a position.
Depending on the size of the rides and the area, you may even be trained on multiple rides. In Fantasyland, rides are broken down into complexes, (Teacups, Pooh, Snow; Philhar, Dumbo; Carousel, Peter Pan, Small World.) You learn every position on every ride on your complex. Some areas may even cross train you later on for other rides or complexes. My CP was the first time Fantasyland cross-trained CPs on multiple complexes, by the time I was done I knew all three!