It really depends on how long he has played games/tournaments. It takes a couple of years for kids to learn the fundamental and applying the techniques in a game takes much longer. You will have to let him play with players of different style/levels and let him understand the game himself...
Overall, I am most satisfied with the new 500ml odorless revolution No 3. It has enough binding strength for most rubbers/blades. And for $40, it is basically the same price as tear mender.
Forehand pendulum serves from a left handed player will usually get a return to the backhand of your partner. So it really depends on whether your partner has better forehand or backhand. Short under spin isn’t really good as it might be returned to anywhere