To repair drywall..smooth the sides of the hole but let the fronts be a little bit wider than the backs. Cut a piece of wood or cardboard a little bit bigger than the hole, put two small holes in the middle of it. Put a strong string or shoelace in it and tie it in front.
Slide this behind the hole and put a long piece of wood or knitting needle through the string and tie it till it holds the backing in place. You could put some glue on the wood so it hits the wall around the hole it so it will stick.
When glue is dry, start putting on the glop of whatever you want or can buy to fix it up. Smooth it till it matches the wall, but just a little bit out from the wall. When dry, remove strings, sand it down, and if necessary to fill hole the string left, do this now and when IT is dry, repaint.
I've done it several times with our many years of large, powerful Dobermans who playfully ran thorough the house and knocked large pieces of furniture against the walls.