One possible plot could be that in a world where Naruto characters co - exist with Dragon Ball Z characters, Naruto is so focused on his own ninja world problems that he completely overlooks the power and significance of the Dragon Balls. For example, villains from the Naruto world might accidentally stumble upon the Dragon Balls and try to use them without understanding their true power. Meanwhile, Goku and his friends are trying to retrieve the balls from this new, unaware threat.
Perhaps in this fanfiction, Naruto is neglected because of a prophecy that foretells of his great power which scares the people in his village. He then stumbles upon a way to enter the Dragon Ball universe. In this new universe, he meets Bulma who is intrigued by his strange powers. With her help, he tries to find a way to either go back to his world and prove his worth or make a new life in the Dragon Ball universe. Along the way, he gets into battles with the likes of Frieza when the tyrant tries to take over a planet that Naruto has come to care about.
It could be Orochimaru. In this fanfiction, Orochimaru might hear rumors about the Dragon Balls and their power to grant wishes. Since he is always seeking power and immortality, he decides to hunt for the Dragon Balls. However, because Naruto is so focused on his own battles against Orochimaru in the ninja world, he fails to realize that Orochimaru's new goal involves the Dragon Balls and the entire Dragon Ball Z universe could be at risk.
One possible plot could be that Naruto and his friends are facing a powerful new enemy in their world. However, this enemy has some sort of connection to the Dragon Balls. Goku and Vegeta sense the strange energy from Naruto's world and travel there using Instant Transmission. They then team up with Naruto and the others. Naruto is amazed by Goku's strength and ki abilities, while Goku is intrigued by Naruto's chakra and ninja skills. Together, they combine their powers to defeat the common foe.
In some Dragon Ball Z fanfiction where Gohan is neglected, it might explore how he copes with the lack of attention. Maybe he turns to self - training more intensely. He could also form unexpected friendships with other characters who notice his isolation.
The plot might involve a new threat emerging on the beach. For example, an alien who is attracted to the energy of the Z - fighters shows up. The fighters then have to protect the beachgoers while also trying not to cause too much destruction. Piccolo could use his powers to create a shield around the beach area to protect everyone.
The plot might involve a villain who has the ability to steal both ki and chakra. This forces Goku and Naruto to team up. Goku, with his Super Saiyan forms, provides brute strength, while Naruto, with his various jutsu like Rasengan and his Sage Mode, offers strategic combat skills. They would have to combine their powers in unique ways to defeat this new threat.
A possible plot could be Gohan focusing on his academic life more. Since he's neglected in the fighting and superhero side of things, he throws himself into his studies and becomes a super - intelligent character who uses his brain to solve problems in the Dragon Ball Z world that others can't with just brute force.
Well, it could be about Naruto characters learning ki techniques from Dragon Ball Z. For example, Naruto might try to learn how to use the Kamehameha wave. It would be really interesting to see how his chakra system would interact with ki energy.
Maybe Naruto, with his godlike powers, enters the Dragon Ball Z universe to stop an evil that neither universe can handle alone.
One possible interesting plot could be that Super 17 gains new powers that are not in the original series. Maybe he discovers a hidden energy within himself that allows him to time - travel. This could lead to him trying to change key events in the Dragon Ball Z universe, creating all kinds of chaos and new storylines for the other characters to deal with.