i think it would be best to have a all around PG,
meaning he has the ball, he handles it. its best for him to be the best guard you got, like a john stockton who can pass, shoot, play D.
your SG can just be a scorer ad cant play D just make sure he cant be stop.
SF is a special element here, because he has to be able to play outside and inside,
but to me you got to have a reall good center to help you get those misses and inside points and defense.
in my experience training G's, training driving can lead to handling and outside shooting. if your training passing it has effect on driving, training jump shotcan effect outside shooting. the only thing i havent experience with other skills is training outside defense. training handling has effects on jump shot and driving.