Hillary's debate prep will be 100% about surviving the types of attacks and tactics Trump used in the Republican debates. She will have a few canned zingers and counter punches. She will spend no time prepping for a deep policy debate because she assumes that Trump will not engage on that level and will instead focus on her scandals and character.
Make Trump a policy detail master. Take away the one remaining argument for Hillary - that she has a deep knowledge and understanding of policy. Ask her questions she can't answer on specifics and demonstrate that Trump DOES know.
Everyone knows Hillary is corrupt. Everyone can make their own Crooked Hillary remarks. Blow this bitch out of the water with intelligence and depth and she can not recover.