I been reading some threads here and there, and the general consensus is that Terumi Mei is the weakest of all five kage, and how multiple ninjas in the narutoverse will own her. With two kekkei genkai, earth, fire, and water natures; not to mention Kirigakure no Jutsu (which is only useless...
Besides Madara being his tutor, i believe he has a couple tricks up his sleeve. I was confused as to why he wasn't at first and i think it's because of the aforementioned counters, chakra preservation, and some sort of rinnegan ace card.