@Slug Princess, one is indeed superior to Tsunade when having the Eternal Mangekyō Sharingan, irrespective of his talent. The Mangekyō Sharingan grants you super powerful abilities, designed for killing victims hopelessly. Even Obito, who was considered to be one of the more untalented shinobi of his clan, slaughtered an Anbu squad of Kirigakure with just 15 years, after just awakening one Mangekyō Sharingan, and if the story taught us one, is that the Uchiha are a naturally talented and skilled clan. The EMS however was praised even before the MS to be the 'true power'. There is no doubt, that Tsunade would hopelessly lose against any user of the MS and EMS in history of the Uchiha.
To get back to your view that Tsunade could tank Madaras techniques. What she tanked were actually Katon techniques, Susanoos Yasaka no Magatama and the sword she was stabbed with, as Madara was toying with them an the fight was limited by the plot. Susanoo has already proven, that it can turn its opponents to paste with one hit, cut body parts of with just a single stroke of its fingertips (seen against Nagato) and smash even Kimimaros bones, which were supposed to be harder than steel and were in this case even supported by Kabutos Senchakra, which increases the power of the techniques.
Tsunade is clearly not able to tank the techniques of the Mangekyou Sharingan, if it comes to a serious clash. In a fight which isn't determined by the plot, Susanoo won't just stab Tsunade with a sword but turn her to paste with a single punch like against Danzo or slaughter her in pieces with a stroke which cut Kimimaros bones. Amaterasu will hit her body, burn her in a fast progress to ashes and kill her by this way, too. It should also be clear, that Tsukuyomi gives her such a mental stress she won't be able to deal with, no matter how strong her will is. The humans mentality is their weakest point after all and Itachi doesn't have limits within his Tsukuyomi, as he controls time and space. She, as a healer, healed Kakashi from a mental damage he received, not she herself and the level of torture Itachi caused to Kakashi was marginal above, if we consider that Itachi can do anything he wants within Tsukuyomi. In Tsukuyomi, Itachi can set Tsunade on fire, tear her into pieces and squish her slowly to paste by full awareness, while showing her pictures of Dan and Nawaki dying by the worst scenarios, for days. She can't heal herself after experiencing such a mental trauma and falling into coma, if not being left dead, what is absolutely the case if one has experienced too much of mental stress.
