That's the very thing I hate about naruto
Naruto: Trained for SM
Fought Kurama and trained for KCM
Only BM he got without training, he still had to befriend Kurama. /:
Sasuke trained hard for those 2.5 years, he mastered his Sharingan, got MS from learning the truth about Itachi.
EMS= Free from implanting Itachi's eyes, so it's about the same level as Naruto getting BM, though Sasuke just took the dead person's eyes and put them in, no befriending needed.
BSM= Already trained for and had SM, why can't he mix the powerup he traine for together with the one he had? You act like he got renningan or something he never had in his arsenal before.