lets say that madara has the same chakra of the vessel of the gedo mazo or that he is the same chakra has the tail beasts have , or even more chakra than the tail beasts , madara said it himself that , he has a chakra of a tail beast (and i bet that he has more chakra than a tail beast itself) because , back at the 5 summit arc , raikage went "beast mode" and Karin said herself , that his chakra "ratio" was the same of the tailed beast , so... if you do 1 + 1 = 2 , that measn that the chakra of raikage alone (of the tailed beasts ratio) vs Edo-Madara couldn't defeat him.
that means that edo-madara and madara alive itself have more chakra than the raikage.
go read the fight of Madara vs the kages , the chapter 577.
and also go read the ultimate showdown of Itachi vs Sasuke , have fun and remember , read everything.