Add to all that the ability to summon and fully control Kyuubi, and you have a man capable of defeating the five Kage on his own indeed, I wouldn't even say with high difficulty.
People need to realize how overpowered that man is. Fighting him is like fighting an optimized, totally overpowered, world-on-fire-setting Itachi (without Totsuka no Tsurugi and Yata no Kagami admittedly, but a huger, walking Susanoo in return) with support from Kyuubi. Insane.
Now, Edo Madara is a totally different story. He already dragged the Kage into a corner, yet he's only toying with them. He didn't use any Rinnegan technique aside from Fujutsu Kyuin, he didn't use Amaterasu, he didn't use Tsukuyomi and he didn't even use his full Susanoo - they already have problems with his version 2 (or 1.5). Just imagine that, five Kage having trouble overcoming one technique. He's not using a third meteor, either. He could even use Izanagi in a worst case scenario. Yes, Madara is more than just a beast.