One interesting idea could be a Naruto who uses his super intelligence to outwit his enemies in new and unexpected ways. For example, he might be able to analyze an opponent's fighting style instantly and come up with a perfect counter - strategy on the fly.
Another idea could be that Naruto's super intelligence allows him to understand the political and social structures of the ninja world better. He uses this knowledge to bring about peace in a more diplomatic way, rather than just through combat. He might negotiate treaties, solve disputes between villages, and promote cooperation among different ninja clans.
Maybe a fanfic where all the characters are transported to a modern-day world. Naruto would have to adapt to things like technology while still trying to use his ninja skills. He could end up using his shadow clones to do multiple jobs at once to earn money and also keep his ninja training going.
One idea could be a super soldier from another land coming to the Naruto world with unique jutsu that no one has seen before. This could create a lot of mystery and excitement as the Naruto characters try to figure out this new threat or ally.
Well, you could have a story where a new villain emerges in the combined Naruto - Super Smash Bros world. This villain has the power to steal the abilities of the characters. Naruto and his comrades, along with the Smash Bros characters, have to team up to stop this villain. They go on a journey across different stages of the Smash Bros game to find the source of the villain's power and defeat him. Along the way, there are many battles, character development, and some humorous moments as the two different groups of characters interact.
Sasuke would be a likely character. Their rivalry could take on a new dimension as Naruto's super intelligence might make Sasuke more intrigued or even a bit jealous. They could have more complex conversations about strategy and the future of the ninja world.
One idea could be to create a fanfic where characters from different game universes within Super Smash Bros. form an unexpected alliance to defeat a new, powerful villain. For example, Mario and Link teaming up with Kirby to take on a dark entity that threatens the Smash universe.
One idea could be that Naruto somehow gets transported into the Super Mario world. He could use his ninja skills to help Mario defeat Bowser in a unique way. For example, Naruto's shadow clone jutsu could be used to create multiple distractions while Mario sneaks up on Bowser.
One idea could be a crossover where Naruto characters learn the Kaio - ken technique from DBZ. It would add a new power - up dynamic to the Naruto universe.
There are fanfictions where Naruto becomes an intelligent diplomat in the ninja world. He uses his intelligence to resolve conflicts between different villages. Instead of relying solely on force, he studies the history and politics of each village and comes up with diplomatic solutions that benefit everyone. This shows a new side of Naruto that is quite different from the original story.
You could write a fanfic about the backstories of how the characters got invited to the Smash Bros tournament. Maybe there's some sort of secret council that decides who gets to participate, and there are some political intrigues among the different game worlds regarding this. So, like, Sonic's world is trying to get more representation in the tournament, but there are some forces that are against it.
A cool fanfiction concept would be a tournament where characters from both Dragon Ball Super and Naruto universes participate. It would be exciting to see how Naruto's clones would fare against Goku's Instant Transmission or Vegeta's Galick Gun.