Currently, it seems that Isshiki Otsutsuki is the strongest foe Naruto has ever faced. Not only does he have insane strength, but his ocular jutsu, the Sukunahikona, is dangerous on another level. It can change the size of matter in himself and non-living things.
Since the start of Naruto, Sakura was infamous for her anger issues. She was very rude to Naruto, often punching him over minor things. Sakura's exaggerated anger was so prevalent that many fans grew to hate her.
1) Hashirama Senju
Hashirama was undefeated in his lifetime. Hashirama defeated Madara Uchiha, who was said to be inferior to him even with Eternal Mangekyo Sharingan.
Naruto: 10 Powers That Make Kaguya Otsutsuki An Absolute God - IMDb. In the renowned series Naruto created by Masashi Kishimoto, Kaguya Otsutsuki is a character who can be considered to be the main catalyst triggering the various events and conflicts that take place in both the manga and anime.
While there's no denying that Itachi is powerful, Madara is simply stronger, whichever way you look at it. With the powers of the 10 Tails and the Six Paths at his disposal, Madara is miles ahead of Itachi, and there's no way the latter can even put up a fight.
Hashirama Senju, aka the First Hokage, was the only one who could ever beat Madara Uchiha in life.
1) Madara Uchiha
This man was able to tame tailed beasts which really showcased his strength. As a child, Madara was able to awaken his Sharingan with one Tomoe in each eye. His mastery of the Sharingan and jutsu capabilities makes him far stronger than Kakashi.
Naruto and Sasuke are arguably the most powerful characters by the end of the Naruto Shippuden anime, so it goes without saying that Might Guy would stand no chance against Naruto in his Sage of Six Paths mode, or against Sasuke using his Rinnegan.
He is dubbed by most to be the strongest shinobi in history. Sasuke himself admitted this fact. In the end, while Sasuke may not be able to beat Naruto, even with his perceived weakened state in Boruto, the two did become friends again. A combination of powers that are said to be able to destroy the entire world.
Pain killed Kakashi during his attack on the Hidden Leaf Village, but that was before a lot of training and the addition of the second Mangekyou Sharingan eye. With that enhanced power, Kakashi would be able to slay even the likes of Pain/Nagato.
Ten-Tails Obito. Something that was hinted at during the majority of the Fourth Great Ninja War is that becoming the Ten-Tails Jinchuuriki was the ultimate power. Having the abilities of the Sage of the Six Paths would make any opponent unbeatable, and yet, Obito managed to lose in a match of morals to Naruto.
Sasuke: Who Has Won More Fights. In all of Naruto, Naruto and Sasuke have fought five times. The first, which was only revealed during a Naruto Shippuden flashback, took place when Naruto and Sasuke were still at the Ninja Academy – and it ended with Sasuke's victory.
Even with his Rinnegan powers and Uzumaki Chakra, Pain was nowhere near as powerful as the original user. As a result, he is one of the Naruto characters who will never defeat Madara.
Conversation. Sasuke, giving us hints as to the future of Boruto and Sarada. Boruto will surpass Naruto. Sarada will become a hokage, technically also surpassing Naruto.
Essentially, this means that Naruto has an eternity to train and get stronger. In this eternity, Naruto can easily devise ways to take his powers to the next level. He can improve upon his Sage Mode and develop new forms of it, or he can develop new forms of jutsu that would be unique to him.
It is a lot clearer in Boruto's case because he is the protagonist of the series. He was also given the Jougan, which is supposed to be quite strong, and the show has to explore it further to understand its true potential. Therefore, it is highly likely that Boruto will surpass his father in the series eventually.
Itachi wasn't strong, he was super smart. Obito feared his smartness. He knew Itachi would destroy any plan of obito as long as he's alive. Obito was not afraid of dying, he was just afraid of his plan getting ruined.
But Jiraiya not only fought Pain alone in his territory but almost defeated him as well. However, in front of Itachi's Tsukuyomi and Amaterasu, his strength might not be enough. As a result, Jiraiya is a Naruto character who can never defeat Itachi.
11 CAN'T DEFEAT: Kakashi Hatake
Furthermore, Sasuke was able to obtain the Rinnegan Eye and the Eternal Mangekyo, giving him another edge against Kakashi. While Kakashi is a brilliant tactician and generally a powerful warrior, he just wouldn't be able to measure up to Sasuke Uchiha as he is now.