Madara is able to to make 25 mokuton clones, all wielding the rinnegan and EMS not to mention respective abilities for each doujutsu but also the ability to act co-ordinately without madara's actual presence. Based on Mokuton's composition Pretapath will render it useless on contact and this goes for each clone. Madara has already stated that his EMS is able to see throuhgh hashirama's mokuton bunshin and also has the abilitiy to anticipate attacks. Given that he has his edo abilities, he is able to use all the jutsu he copied from hashirama. Added to this, the rinnegan is a greater potential threat in comparison with the kyuubi, which hashirama himself stated was overwhelming. Hokage's 2-4, Orochimaru and Taka are all inferior to EMS Madara much less his Edo state that is maxed beyond his prime. Obito and Madara has the option of re-connecting to the Juubi (via physical mokuton attributes) at will. They're all edo's and can't die or be depleted chakra wise, which could provide a problem but nothing critical.
