The strongest ninjutsu is Chibaku Tensei because it was used to create the moon and it has trapped the Ten-tails jinjurinki. That's hard to say. Amaterasu is the strongest Fire Style jutsu, Rasenshuriken is the strongest Wind Style jutsu, Water Dragon is the strongest Water Style jutsu, Kirin is the strongest Lightning Style jutsu, C0 (Ultimate Art) is the strongest Earth Style jutsu, Tsukiyomi is the strongest Genjutsu, and Gentle Fist is the strongest Taijutsu. Also, the strongest Bunshinjutsu is Multi Shadow Clone Jutsu, the strongest Fuinjustu is Reaper Death Seal, the strongest Juinjutsu are Heaven's Curse Mark and Earth's Curse Mark, the strongest Senjutsu is Ultra Giant Rasengan, and the strongest Tensei Ninjutsu is Samsara of Heavenly Life. The strongest Dojutsu is Rinnegan and the strongest Kekkei Genkai (that's NOT a Dojutsu) is Wood Style (in my opinion). There are several extremely powerful jutsu that can't be put into catergories.
it's probably the sage jutsu or the sharingan.
The Naruto world has a kind of rock papers scissors thing when it comes to elemental jutsus, so even though Amaterasu is classified as the strongest fire ninjutsu, it could presumably be matched by a water jutsu. There is no definitive "strongest jutsu", especially when you could measure it in different ways. For instance, is it a supporting jutsu? Is it a Genjutsu? Is it a taijutsu? They are all different.
Well, as of now, strongest jutsu is the Shinsusenju, or several thousand hands, by Hashirama Senju, beating both Madara and Kurama. And also can tower over hundreds of mountains, and has a chance of competing with the Juubi. And also, it is considered as a Senjutsu due to Hashirama entering Sage Mode. Then, the strongest genjutsu is the Infinite Tsukoyumi, same as Kotoamatsukami, but having a wider range, but not yet performed, this is a jutsu made by Madara, Obito, and the Ten-Tails. Strongest Kinjutsu is Eight Gates, due to the fact that you can acquire power greater than a Kage, but will also cost you your life. Strongest Nuke Jutsu, well ofcourse, the Bijuu Dama (tailed beast bomb). Strongest Taijutsu, Hirudora. Fastest Jutsu, Flying Thunder God. This is to only get you guyz updated to the manga. But not spoilers.