One common theme is power comparison. Fans like to see how the powerful characters from each series stack up against each other. Another is adventure. Combining the grand adventures of One Piece with the epic battles of Dragonball Z.
Sure. There are many fanfics out there that combine these two great series. One popular one might be those that feature crossovers in battles. For example, Luffy from One Piece might team up with Goku from Dragonball Z to fight a common enemy. You can usually find such fanfics on popular fanfiction websites like FanFiction.net or Archive of Our Own.
Another plot could involve the Devil Fruits from One Piece and the Ki powers in Dragonball. For example, a character could eat a Devil Fruit that gives them the ability to manipulate Ki in a unique way. Or perhaps a Dragonball character accidentally eats a Devil Fruit while visiting the One Piece world and has to deal with the consequences, like not being able to swim.
Luffy and Goku would be an amazing combination. Luffy's carefree and determined nature combined with Goku's love for fighting and protecting the innocent could lead to some really fun and exciting adventures. They could learn from each other's fighting styles, with Luffy being inspired by Goku's Ki - based attacks and Goku being intrigued by Luffy's Devil Fruit abilities.
One of the best crossovers could be the combination of power - ups. For example, Naruto's Sage Mode combined with Goku's Super Saiyan form. It would be interesting to see how their powers interact and if they could learn from each other's fighting styles.
In a crossover fanfiction, it could be that the power of Devil Fruits from One Piece becomes known in the Dragonball universe. Vegeta, being his prideful self, wants to obtain a Devil Fruit power to make himself even stronger. He travels to the One Piece world and accidentally ends up on the Thousand Sunny. The Straw Hat crew initially see him as a threat but then realize they can help each other. They end up in a big adventure together where they combine their powers to fight a new common enemy that threatens both universes.
Bulma from Dragon Ball Z in Naruto fanfiction has potential. She is smart and resourceful. In the Naruto world, she could use her intelligence to create new technologies or help with strategic planning during battles, and her interactions with the ninja characters would add a new dimension to the story.
One popular 'One Piece Crocodile x Doflamingo fanfic' is 'The Unlikely Alliance'. It delves into their complex relationship within the One Piece universe. The story shows how their different motives and personalities interact in unexpected ways.
Well, a cool concept for Pokemon and Dragonball Z fanfiction could be that the energy in the Dragonball Z world affects Pokemon in strange ways. For example, Pikachu could learn to use Ki blasts. Also, a story where the Z - fighters visit the Pokemon regions and have to participate in Pokemon battles to save the day. And a more complex idea would be a fusion of the two worlds' power systems. Say, a Pokemon trainer figures out how to use Ki to enhance their Pokemon's abilities, and in turn, the Pokemon help the trainer in combat against the powerful foes in the Dragonball Z world.
There might be a fanfiction that focuses on Vegeta and Bulma's relationship in a more in - depth way. It could show how they handle their differences while also dealing with the Saiyan - Earthling cultural clashes. This type of story can add a lot of depth to their relationship and show sides of the characters that we don't see as much in the official story.