Here is a teaching aid I have had great results with recently for the riseball. I am certain it will work for other pitches also.
When one of my pitchers is having a tough time getting her riseball to move, I have her go through her pitching motion in super slow motion. I have her stop at each section of the pitch so I can assure her and myself that her mechanics are correct.
You will be able to locate problems in the mechanics area a lot faster this way. In most cases, the pitchers are merely sliding their hand under the ball to give the proper rotation for the riseball, however, if you want a riseball that RIPS, try this. Sequence the riseball mechanics and locate the position when the wrist turns over. A lot of pitchers throw very good "floaters" that are tough to hit, but why not have one the RIPS?? The key to this is too have the wrist turn over and propel the ball with tons of rotation. The way to do this is to have the wrist turn over very late in the pitch. This will impart some incredible rotation to the ball and will create remarkable movement.