What is Sasuke's most powerful jutsu?

windmill raesagun. which at the time was an incomplete jutsu by the 4th hokage.

eventually Naruto learned about this incomplete jutsu after being told by kakashi sensei. Naruto needed to complete this (or any new justu) so he wouldn't have to rely on the power of the Nine-tailed Fox. after kakashi sensei came up with this genious plan to make years of training into mear days ...and how you might ask? watch the sesons to much to explain ....so naruto invented it and it is the best

i think it would be vermillon rasengan,chidori lamet, odma rasengan and double chidori quake

I'm a ninth degree black belt in Ninjutsu. I would recommend Dr. Masaaki Hatsumi's Bujinkan organization for authentic Ninjutsu instruction. He is the Soke and headmaster of nine separate martial arts. He currently is teaching those arts to nine masters of Western Ninjutsu, a tenth art that originated in the U.S. Central Intelligence Agency. Ninjutsu is a great martial art that offers some of the best internal training around - the emotional feeling of the training is a wonderful treat that you have to experience to fully understand. Dr. Hatsumi has a cousin named Tanemura who leads an organization called the Genbukan and there is an instructor in Indonesia who is teaching a personally crafted system that resembles Brazilian Jujutsu, but I would recommend the Bujinkan as the best Ninjutsu around. Dr. Hatsumi has been investigated by Japanese scholars to validate the authenticity of his lineage and Japan's government has called him a National Treasure because he has rooms full of scrolls that are nine hundred years old to prove he is the true Grandmaster of all Ninjas.