Well, in a One Piece and Dragonball Z crossover fanfiction, the art styles are quite different, but that could add to the charm. For example, the colorful and outlandish characters from One Piece would contrast with the more muscular and intense look of Dragonball Z characters. Maybe the Straw Hat crew would be intrigued by the Dragon Balls and their power to grant wishes. They could embark on a journey to find all the Dragon Balls, while also dealing with the likes of Cell or Majin Buu who are interested in their unique abilities.
Zoro and Piccolo would also make for an interesting pair. Zoro is a master swordsman always seeking to become stronger, and Piccolo is a powerful Namekian with great combat skills. They could have some intense training sessions together, sharing their knowledge of combat and power - up techniques.
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.
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.
Zoro and Vegeta would also have a great interaction. Zoro, with his strong sense of honor and his goal of becoming the world's greatest swordsman, would be a worthy opponent for Vegeta. Vegeta would be interested in Zoro's swordsmanship and might even see him as a potential rival. They could have some intense training sessions together, sharing their knowledge of combat and power - up techniques.
Well, one possible plot could be that Naruto and Goku somehow end up in each other's universes. Naruto could be intrigued by the concept of ki and try to learn it, while Goku might be interested in Naruto's ninja skills like shadow clones. They could team up to fight a common enemy, perhaps a new villain created by fusing some of the bad guys from both universes, like a combination of Orochimaru and Frieza.
One interesting plot could be that the Pokemons are suddenly exposed to the energy of the Dragon Balls. Some Pokemons start to gain Saiyan - like abilities. For example, Pikachu could become Super Saiyan Pikachu, with its electric powers amplified to an extreme level. It could then face off against powerful Pokemon villains in a whole new way, with the fast - paced combat style of Dragonball Z.
In a crossover, it really depends on how the powers are combined. If Naruto could somehow combine the Nine - Tails' chakra with Sage Mode and then learn some ki techniques from the Dragonball Z side, he could be extremely powerful. But Goku has been training for a long time and has access to godly ki. So he would be a top contender as well. Vegeta too, with his own determination and power - ups, could also be in the running for the strongest.
Well, it could be really exciting. Picture Naruto with Goku's ability to go Super Saiyan. Maybe Naruto could learn the Kaio - ken technique. The story could involve the two universes colliding, with villains from both sides teaming up. So Naruto and his friends from Konoha would have to join forces with Goku and the Z - fighters to save both their worlds.