What is a good diet to gain weight muscle weight?

Proper exercise&prot. Weight training builds muscle with fewer reps and more resistance faster! however more injuries occur. A 7/4/3. Max rep is ideal. Finally you need one gran per lb of body weight. This is higher if your protein intake is heavily plant protein base because of a lower protein efficiency index. Read my chapter in freddy fu's "sports medicine" on "powerlifting & weightlifting.".
High protein. High protein but make sure you also have a balance of fats and carbs. Natural proteins are better than supplements or drinks.