We have another one of the tail beast techniques naruto only learns how to use after getting the sage powers and it's broken basically, the user can boil their own chakra to increase their own physical strength.
Take the incredibly broken Russian shuriken and add the four tails chakra Series and you get this monstrosity the rating shuriken is already enough to take out almost anything that isn't a six parts character so how strong is this version.
The last naruto movie was pretty much high tier naruto and Hinata fan service and it all built up to this technique naruto concentrates all of his and Kurama's chakra into one hand and punches someone really really hard.
The Bijuu Dama is not only one of naruto's strongest techniques but one of the most recognizable Jutsu in the entire naruto world naruto himself has used this thing many many times to great effect.
The Truth-Seeking orbs are probably one of the strongest techniques in the entire series the only reason this isn't top five is that naruto seemed like he had no idea how to use the things these orbs are pretty much made of every chakra nature you can think of and can
Say one thing about naruto says he learned how to name his Jutsus from his father, yes the name doesn't exactly leave a lot of room for the mystery here, this is the biggest ball of Rasengan that anyone in the entire show can make.