If madara has been stuck in that cave forever, why didnt he just make zetsu clone him and then carry out the missions for him. doesn't seem like he would really need Obito to do what he needs him to do.
What would stop Zetsu from killing Madara? and by the way Zetsu copy ''Similiar'' chakra and he can't use all the jutsu's he has and i don't think the body of a 150 year old will be able to jump over tree's ndshit.