We've removed damaged drywall on our bathroom walls, and would like the walls to be thin tongue-and-groove planks. Is anything material except the tongue and groove required on the studs?
You should be careful in your choice of wall paneling material and its preparation. Not all T&G planks are suitable for walls period, and fewer still are suitable for bathrooms. Ensure your planks are sealed on all sides to minimize risk of warping.
For more flexibility, install a standard drywall wall surface. Then you can attach decorative paneling over that without compromising critical functions of the wall.