Another aspect to consider is how the Super Saiyan transformation would affect the relationships in the Naruto world. If Sasuke were to gain Super Saiyan powers, it could either drive him further away from Naruto due to the newfound power or bring them closer as they explore the new abilities together. Also, the concept of ki from Dragon Ball and chakra in Naruto could be merged, creating a whole new type of energy for the characters to utilize.
A Super Saiyan in Naruto fanfiction could be a result of a dimensional rift. Maybe a portal opens between the Naruto and Dragon Ball universes and some Saiyan energy seeps through, affecting a Naruto character. This would be an interesting plot device as it would introduce an alien concept to the ninja world.
Well, it depends on how you define fanfiction. Technically, Dragon Ball Super is an official continuation of the Dragon Ball series. However, it does have elements that feel like fanfiction. For example, some of the power - levels and new forms introduced seem a bit outlandish and more like what a passionate fan might come up with rather than a strictly logical progression from the original story. But it's still an official part of the franchise so it's a bit of a gray area.
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.
One interesting crossover could be a battle between Naruto's Rasengan and Goku's Kamehameha. It would be epic to see the different energy forms collide. Maybe Naruto could learn some of Goku's training techniques and vice versa, like Naruto trying to achieve Super Saiyan levels of power or Goku learning about chakra control.
Yes, there are likely some fanfictions out there. You can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just type in the relevant keywords and see what pops up.
A great fanfiction idea is a fusion of the power systems. For example, a story where characters can combine chakra and ki. Naruto could try to use ki - enhanced rasengan or Goku could use a chakra - based Kamehameha. It would be an exciting exploration of both universes' power concepts.