I THINK THAT HASHIRAMA DEFEATED MADARA DUE TO THE FACT THROUGH OUT THE SERIES HISTORY IT STATES THAT THEY WOULD BE CONSTANTLY BATTLING EACH OTHER AND HE WOULD OF UNDERSTOOD HOW THE MS WORKED THEREFORE KNOWING ITS WEAKPOINTS ALONG WITH HIS CLANS KNOWLEDGE OF JUTSU( The Senju clan gained their fame in the era before the founding of the hidden villages. Where other clans focused on mastering one particular skill, the Senju were masters in all skills, from ninjutsu, to taijutsu, to genjutsu. Because of this, they were feared as "the clan with a thousand skills" (「千の手を持つ一族」, "sen no te o motsu ichizoku"), which gave them their name Senju (千手, "a thousand skills", "a thousand hands").ALONG WITH HIS MAD WOOD RELEASE JUTSU IT SEEMS HE HAD GOOD CONTROL OF NATURE CHAKRA COMPARED TO MS AND THE EMS ALL THE TECHNIQUES ARE MORE RELATED TO A DARKER POWER AND RAW CHAKRA ,WHERE AS HASHIRAMA CHAKRA CAME FROM NATURE AND WHO KNOWS DID HE HAVE THE OTHER TAILED BEASTS FIGHTING THE 9 TAILS? WHICH ALSO COULD OF SWAYED THE BATTLE AGAINST MADARA COS THE TAILED BEASTS COULD ALSO HOLD THE SECRET TO DEFEATING THE 9TAILS... >>> THATS JUST MY OPINION