Perhaps in the fanfic, the One for All quirk could be linked to Naruto's Nine - Tails chakra. The two powerful forces could either clash or merge, creating a completely new power dynamic within Naruto. This could also cause internal struggles for Naruto as he tries to control both the wild nature of the Nine - Tails and the unique properties of One for All.
One plot idea could be a character from the All for One world somehow ending up in the Naruto universe and having to adapt to the chakra system. Maybe they try to steal chakra powers like they steal quirks in their own world.
One idea could be a crossover where Naruto's world is invaded by villains from Hero Academia led by All for One. Naruto and his friends team up with the heroes from Hero Academia to fight back. They could learn new techniques from each other, like the heroes learning chakra control from Naruto.
A 'naruto all elements fanfic' could center around Naruto being cursed with an imbalance of all the elements within him. He has to find a way to control and harmonize them, perhaps with the help of an ancient sage who once mastered all elements. This could lead to new and powerful jutsu development.
One idea could be to focus on Naruto's first day at the Ninja Academy. You could show his nervousness and excitement, and how he interacts with his classmates like Sasuke and Sakura for the very first time. Maybe include a small prank he tries to pull on Iruka-sensei on that day.
One idea could be a character having the 'All For One' quirk in the Naruto universe and using it to steal other ninja's unique abilities. For example, they might target a Sharingan user to gain that power. Another plot could involve a group trying to stop this 'All For One' - like - character from disrupting the balance of power in the ninja world. And perhaps the character with 'All For One' has a hidden motive related to an ancient prophecy in the Naruto world.
Well, a really cool plot might be that Orochimaru, always interested in new powers, somehow gets his hands on the 'All for One' concept. He could start using it to assimilate the powers of different beasts, like the tailed beasts, in a new and different way than just sealing them. Or perhaps a young genin discovers they have the 'All for One' ability. They initially use it to help their friends by taking on some of their weaknesses, but then it attracts the wrong kind of attention from the Akatsuki, who see it as a powerful tool for their own goals. Also, a time - travel plot where a character from the future with the 'All for One' ability comes back to the Naruto world to change the course of history, either for good or bad.
One interesting plotline could be the exploration of how the 'One for All' power from My Hero Academia would interact with the Naruto universe. For example, how a character with 'One for All' might face off against powerful ninjas. Maybe they use the power in unique ways during battles, like combining it with chakra-based jutsus.
One idea could be a fanfic where Naruto decides to go on solo missions but ends up befriending a mysterious creature that gives him unique powers. Another could be about Naruto forming his own one - man team in a parallel universe where he has different skills and challenges. A third idea might be a fanfic where Naruto is on a one - man team to explore an ancient and dangerous land filled with unknown ninja techniques.
A really cool idea for this crossover fanfic could be a fusion of powers. For example, what if Zoro got some of Sasuke's Sharingan abilities? He could use it to predict his opponents' moves even better. On the other side, what if Nami got some basic ninjutsu skills like the Clone Technique? She could use it to trick pirates while stealing their treasure. Also, the story could be about a search for a special item that has significance in both worlds. This item could be a key to unlocking a powerful force that could change the balance of power in both the Naruto and One Piece universes.
Another interesting idea is a story where the Devil Fruits from One Piece exist in the Naruto world. Naruto characters could be tempted by the powers of the Devil Fruits, and some might even consume them, leading to a whole new set of abilities and power dynamics. This could also cause conflicts between those who have Devil Fruit powers and those who rely on chakra.