solo training

serve,footwork can be trained without partner...but u should have a partner to receive your serve,and so you can know what's the spin of your serve

I've written some thoughts about training by yourself (including service practice, shadow play, footwork drills, video analysis, robots, exercise, and mental training), which you might find helpful.

That he does it correctly without the ball shows, in part, the value of shadow practice.  The strokes should be learned in "muscle memory"  Doing them incorrectly causes you to learn them incorrectly.  When done in the mirror where you can see your errors and correct them, you enable yourself to learn them correctly.  In time you will have corrected your form and your muscle memory will have the proper stroke ingrained.

This practice without the ball is very helpful in training for proper timing of ball contact in relation to the body.  With no ball to deal with you will always practice the contact timing correctly.  Then when you have the ball to deal with you will automatically want to use your feet move to the ball in order to contact the ball the same way you have been doing it in your shadow practice.

You should have your student do the serve practice without the ball until it transfers to doing it correctly with the ball.  This may take time, but it will work.