One possible plot could be that Naruto and Goku end up in a strange new dimension where they have to live together. They start by trying to understand each other's powers. Naruto is amazed by Goku's Saiyan abilities like the Kamehameha wave, while Goku is intrigued by Naruto's ninjutsu. They then team up to face common enemies in this new world. Maybe there are villains from both their universes that have also been brought there. Together, they train and learn from each other, with Naruto teaching Goku about stealth and strategy, and Goku showing Naruto how to push his physical limits even further.
The plot might involve Naruto and Goku living in a shared house. At first, they have cultural clashes as Naruto is from a ninja village with its own traditions and Goku is from a more simple, martial - arts - focused world. But as time passes, they become friends. They could go on adventures together, exploring different parts of the new world they are in. For example, they might discover a hidden place full of powerful energy sources. Goku would be eager to train there to get stronger, and Naruto would see it as an opportunity to learn new skills and protect the place from those who might misuse it.
Well, it could start with some sort of interdimensional or magical event that links the Naruto and Dragon Ball universes. Maybe Goku somehow ends up in the Naruto world and has a relationship there, resulting in Naruto being his son. Then Naruto could inherit some of Goku's powers, like super strength or the ability to fly, on top of his own ninja skills. He might use these new powers to face even greater threats in the Naruto world, like stronger versions of the Akatsuki.
Well, it could be that Naruto is exiled for some reason and has to live in a cave. In the cave, he discovers some ancient secrets or artifacts. These could be related to the origin of chakra or some long - lost ninja techniques. He then uses this knowledge to his advantage and maybe even changes the ninja world for the better.
The plot could involve them facing a common enemy. Since they both come from different but powerful universes, their combined strength would be interesting to explore. They could start as strangers in the fanfic, gradually become friends while living together, and then team up to fight this new threat.
One possibility could be that in his second life, Naruto has all the knowledge from his first life. So he can avoid making the mistakes he made before and become an even stronger ninja much faster. He might also use his past experiences to better understand his friends and enemies, and form different relationships.
Well, the plot could involve Naruto being a huge fan of Goku through some kind of inter - dimensional viewing device. He starts to mimic Goku's training regime, much to the confusion of his friends in Konoha. Then, an evil force from the Dragon Ball universe somehow crosses over to Naruto's world. Naruto, with his new - found inspiration from Goku, decides to take on this threat, and in the process, he might even convince Goku to come and help him save his world. Along the way, there could be lots of comical moments as Naruto tries to explain ninja concepts to Goku and vice - versa.
A plot could be that their worlds start to merge. Sonic's world of Mobius, Naruto's Hidden Leaf Village and Goku's Earth start to blend together. Sonic has to deal with the strange new chakra energy, Naruto is fascinated by Sonic's speed and Goku is intrigued by Naruto's unique jutsus. They have to figure out how to separate the worlds again while also fighting off threats that emerge from the chaos of the merging worlds.
A possible plot could be that Android 18 and Goku are thrown into an alternate dimension where they have to rely on each other to survive. In this dimension, they face challenges that test their friendship and fighting skills. Android 18 might learn some of Goku's signature moves and Goku could learn more about the technology within Android 18.
It could be Frieza. Frieza is a powerful and evil character from Goku's universe. He might see the combined power of Naruto and Goku as a threat and try to eliminate them. He could also be interested in the unique powers that Naruto has, like the Nine - Tailed Fox's chakra, which he might want to use for his own evil purposes.
Well, one possibility is that Goku, with his powerful Saiyan abilities and big heart, teaches Naruto new combat techniques. Maybe he shows Naruto how to better control his chakra by using some of the principles of Ki control in the Saiyan way. For example, Goku could help Naruto reach new levels of power in his Rasengan by adding elements of his Kamehameha's energy concentration.
Perhaps the story could start with Naruto having strange dreams about Goku's life. As the story progresses, he gradually unlocks Goku's powers. He could then use these powers to protect the Hidden Leaf Village in a more powerful way. For instance, when the village is under attack by a powerful enemy, Naruto could transform into a Super Saiyan - like state, shocking his enemies and allies alike. His training would also change, as he'd have to learn to control his new Saiyan powers, which would be a whole new journey for him.