good morning narutobase i was just thinking about this and thought i would get your option
now before i start i wanted to say that the so6p gave his spiritual energy to his older son(uchiha) and the younger son(senju) got his physical energy now keeping this in mind let me begin
now i want you to notice how sasuke's ems susano'o and madara's ems have very similar arms now i believe that is perfect sussno'o and the big susano'o madara summons with the katana and long nose is his perfect sussno'o stabilized.
Now everyone is thinking we know this but what i want to point out is that madara's perfect susano'o stabilzed is not a ems jutsu bt a ems + senju dna while perfect susano'o is the ems jutsu.
To kinda prove this with out images or manga pages note that susano'o is a big mass of spirtual chakra and when madara stabilzed his susano'o it took a physical shape hence why i think senju dna is required.
**im sorry idk how to post images or manga pages from my phone so this theory kinda sucks bt if hou did read thanks and your comment would help me with this theory thanks**