In my opinion he almost do not need to train with a coach. It would be really good to do and proably the best, but there are so much resources on how to play on internet today.
So if you can afford it and have a good coach i think you should hire him.
But a really good start would be to watch videos of these things:
1. the grip.
2. Forehand counter and backhand counter
Many people may tabletennis harder than it is, the strokes are all pretty similar but with different angles and there are no right way to play. If you just learn to counter well, the push is the same but with an open racket angle and the loop is the same but with a closed racket angle. Maybe i made this to simply now, but if you learn to counter correctly there are not much difference.
I do not know how much it would give you if i try to explain, much better to see videos. So i would just say some guidelines:
Grip: it is called shakehandgrip because you shake the handle, so grip it like you are meeting someone. Thumb and index finger should be down on the side and creating the letter V. Try to have the loose skin between thumb and indexfinger in the middle of the blade and try to hold it loosely. Also try to hold the same when playing backhand and forehand.
Backhandcounter: stand pararell with the feet. have tha elbow a bit infront of you, it should not move much, it is like a hinge. Wait for the ball to come to you, you want to hit the ball close to the body, and always infront of the belly button. Then you hit mostly with the forearm and wrist. , and have the elbow steady. Close to the table, more wrist and less elbow and the opposite further away. The loop is the same, you just want to close the racket angle so you hit over the ball and brushes it thin, also important to stop after you have hit the ball.
Forehandcounter: left foot a little infront. Alot of debate about this today, because of the bh oriented play. But i think the left foot infront. If you extend your forarms forward so the arms are almost straigth you will have created an triangle with your feet and where the arms meet eacheother. Try to hit the ball where the arms reach eachother. You always want to have the arm in front of you. I think you should start with the arm almost where your nose is, then you move back the arm, with the stomach, to the side of the body and then you hit the ball in the triangle, and stop the stroke by your nose again. You do not want the arm behind you and you do not want to have to big of a backswing so you get distance between racket and ball. Very important that you move the belly with the arm. Will proably be really hard to do this close to the table and you do not really do not need to do this in the counter. But if you can learn this the forehand loop is basically the same, you only need to close the racket angle and try to brush the ball like you do on the backhand. Try to think the arm and belly like two hinges of a door, they open and close together.
Iy you can just learn a good grip, then become good at backhand counter and forehand counter, then like i said push and loop is almost just a change of angle. The problem with forehand loop comes if you have only counter with the arm, then it becomes difficult to learn a forehandloop because you almost need to learn a new stroke.
Then learn to move well, you only need one forehand loop if you can move well. The chinese do this well. We fat europeans need to be able to become good at two, three fh loops because we move like shit while the chinese only need one.
Everyone can become good at tabletennis.
I thin the secret is to try do the correct technique, do alot of shadow training and play very very very very ridicoulous slow so you do the correct technique. Maybe you should look so you do not have to fast equipment. If you do the correct strokes, you only need to play slow so you get to practice at the strokes alot. We become good at everything we do alot. Then put some footwork in there, and the same applies. Play slow so you get to learn to move well. And train with focus and alot.
So correct technique, many balls over the net all the time, move alot, train as much as possible with as much focus and spirit as possible.
Serve and return is more about feeling, and is not necessary to work on on the moment.
Good luck