Another concept could be that the Nine - Tailed Fox from Naruto somehow gets loose in the One Piece world and its chakra affects Devil Fruits, causing strange mutations. Luffy and his crew then have to team up with Naruto and his friends to find a way to stop the chaos.
A good fanfiction also needs a strong plot. You could start with a conflict that involves all three aspects. Say, a powerful enemy that is a combination of the threats in Naruto and One Piece is threatening the New World. Develop the relationships between the characters from both series. Let them learn from each other and grow. For instance, Zoro could teach Sasuke some new sword techniques, while Naruto could inspire Luffy with his never - give - up attitude.
The 'New World Symphony' has a long - standing history in the world of classical music. Michael Story's arrangement of it could bring new life to the piece. He may have used different musical techniques such as new harmonies or rhythmic patterns. This arrangement might also be influenced by contemporary musical trends, while still maintaining the essence of Dvořák's original masterpiece. It could be a great addition to the body of work related to the 'New World Symphony'.
In a fanfiction where Naruto is a fishman in One Piece, Naruto would face new challenges. For example, dealing with the discrimination that some fishmen face in the One Piece world. But he'd also have new opportunities. He could use his fishman physiology to swim faster and deeper, discover hidden treasures, and maybe even find a way to connect the ninja world with the pirate world. His Nine - Tailed Fox chakra might also have some interesting interactions with the strange powers in One Piece.
The One Piece system could change the relationships between characters. Heroes and villains who previously had no connection might be brought together because of the new elements introduced by the system. For example, the X - Men might have to team up with a group of characters inspired by One Piece pirates to face a common threat that the One Piece system has brought into the Marvel world. This could lead to new storylines and character developments as they learn to work with different personalities and power sets.
Kankuro could use his puppet - making skills to his advantage. He could create puppets that are resistant to the elements in the One Piece world, like water - proof puppets since there are a lot of sea - related challenges there. Also, he could make puppets that can fly to deal with the various islands and different terrains.
He might fit in as a sort of super - strong outsider. Vegeta could be on a quest for his own kind of 'One Piece', which could be something related to power or a way to return to his own universe. His Saiyan abilities would make him a force to be reckoned with. For example, his ability to transform into Super Saiyan forms would be like a new level of power that no one in the One Piece world has seen before. He might start out as an antagonist but could end up teaming up with the Straw Hats if they had a common enemy.
The fanfiction can also add a new dimension to the characters. Chopper's relationship with lemons can show different aspects of his personality. If he's really into studying the lemons, it can highlight his scientific curiosity. And it can create new dynamics within the Straw Hat crew as they interact with Chopper's lemon - related adventures.