I think he could be turned into a Pikachu. Pikachu is known for its spunk and determination, which are traits Naruto also has. Plus, both are quite small but extremely powerful in their own ways. Naruto's energy could be translated into Pikachu's electric powers in an interesting way.
Perhaps there's a special artifact. In the Naruto world, there are many powerful artifacts. If one of these artifacts was somehow connected to the Pokemon world, and Naruto interacted with it, it could trigger the transformation. For example, if an ancient scroll had the power to bridge the two universes and Naruto unknowingly activated it while on a mission, his body could start to change into a Pokemon. This would not only change his physical form but also his abilities, making for a really interesting fanfic plot.
Well, in such a fanfic, it could be a really interesting concept. Maybe it was due to some magic spell or a strange encounter in the Pokemon world. It might lead to various adventures where her friends in the Pokemon series try to find a way to turn her back into her normal self.
It could be a rogue Team Rocket member. Maybe they got their hands on a powerful new device that was meant to capture Pokemon but malfunctioned when aimed at Misty and turned her into stone instead. Now they're trying to cover up their mistake and keep Ash and the others from finding out the truth.
It's possible that as a doll, Misty discovers some hidden abilities or secrets. For instance, she could be able to communicate with certain types of dolls or inanimate objects in the Pokemon world. This could lead to a whole new adventure as she uses this new - found knowledge to help her friends, even in her doll form. The story could also involve some emotional moments as her friends struggle to accept her new form at first but then grow to love and protect her all the same.
One popular 'human turned pokemon x harem fanfic' is 'A New World, A New Me'. It has an interesting plot where the main character, who turns into a pokemon, has various interactions with different pokemon characters in a harem - like setting. The story is well - written with a good balance of adventure and character development.
Well, adventure is a big theme. Since it's set in the pokemon world, there are always new places to explore and challenges to face. Also, acceptance is common. The main character has to accept their new form as a pokemon and the relationships that come with the harem. The harem aspect often involves themes of love, loyalty, and sometimes jealousy among the pokemon in the harem.
One possibility is that Naruto's transformation into a robot could change his relationships. His friends might be initially shocked and have to learn to trust this new robotic version of him. He could also face new enemies who are specifically targeting him because of his unique robotic - ninja nature. His sensei might have to train him in different ways to make use of his robotic abilities, like teaching him how to maintain and upgrade his robotic parts.
It could lead to a whole new dynamic in the story. Maybe Naruto's relationships with other characters would change, and her ninja skills might be perceived differently.
From Naruto, obviously Naruto himself would be a main character. Sasuke could also be there, maybe he's initially skeptical about the Pokemon but then warms up to them. In the Pokemon world, Ash and Pikachu are must - haves. Misty and Brock could also show up to offer their expertise in Pokemon training.