Drywall repairs can be very serious sometimes, I have been involved  in some of the most extreme situations. In this segment which involves horrible mold damaged drywall,after drywall had been removed the wood framing was treated with Zep mil-decide mildew and mold treatment.New Gypsum was applied, using Easy sand brand products which is a powder form joint and patching compound,and Fiba tape (adhesive fiberglass seam tape). My favorite brand tools are Marshall town, wallboard, pro form. 3m,Stanley,Ry-obi,Gator,Corning Insulation.