One idea could be a character who can transform into solid earth structures, like mountains or cliffs, for both offensive and defensive purposes. This would add a new dynamic to battles in the Naruto universe.
In a Naruto solid transformation fanfic, a character could transform into solid lightning. It's not a typical form of lightning ninjutsu. Instead of just shooting bolts, they become a being made of solid electricity, able to move at incredible speeds and deliver powerful shocks on contact.
In 'naruto solid transformation fanfiction', there could be the concept of Naruto using solid transformation to create complex structures. For example, he could transform into a solid fortress that his comrades can take shelter in during battles. Also, perhaps he can transform parts of his body into solid weapons with special properties. Say, his arm could become a sword made of some super - dense, unbreakable material.
Perhaps a fanfic where Naruto's Solid Henge goes wrong and he accidentally creates a bunch of strange and uncontrollable objects. This could lead to a comical adventure as he tries to fix his mistakes with the help of his friends like Sasuke and Sakura.
A unique solid transformation could be one that allows the user to transform into a solid form based on their emotions. For example, if they're angry, they turn into a solid, spiky mass of energy. This would be different from the normal elemental-based transformations in Naruto.
One idea could be to have Naruto characters infiltrate a Metal Gear - like facility. For example, Naruto's shadow clones could be used to distract the guards while Sasuke tries to find and disable the main weapon system, similar to how Solid Snake would operate in the Metal Gear Solid games.
One idea could be Naruto using the Solid Henge to create complex and long - lasting structures for strategic purposes in a battle. For example, he could make a huge fortress that the enemy has to break through, adding an interesting twist to the fight.
One idea could be a young protagonist who discovers they have a dormant dragon - transformation gene. They start having strange dreams and then one day, during a moment of extreme danger or high emotion, they transform into a dragon for the first time. Their journey could then be about learning to control this new power and finding out the origin of their dragon - like abilities.
One idea could be a trainer who accidentally gets exposed to a strange energy and starts to transform into a Pokemon. They then have to figure out how to reverse the process while also experiencing the world from a Pokemon's perspective.
Well, for animal transformation fanfic, you could have a story where a person transforms into a cat. They would then have to adapt to the feline lifestyle - climbing trees, chasing mice (or toys that look like mice), and napping in sunny spots. Or perhaps a transformation into a dragon. This would involve dealing with the huge size, breathing fire (if it's that kind of dragon), and being feared or revered by the people in the story's world. It could be really cool to write about how the character copes with this new identity.
Another interesting concept is a transformation game within the fanfiction where the characters compete to master unique transformations. For example, Sasuke could be challenged to transform into a form that combines his Sharingan powers with a powerful beast, like a dragon, to gain an edge over his opponents.
One interesting idea could be the unique forms the characters take. For example, Naruto might transform into a giant fox - like monster with even more powerful chakra abilities than his regular Nine - Tails form. Another idea could be how the transformation affects their relationships. Maybe Sasuke would view Naruto differently if he had a more monstrous transformation. Also, the origin of these monster transformations could be explored, like if it was a result of some ancient jutsu gone wrong or a new power that emerged in the ninja world.