Maybe a fanfic where a group of Pokemon fuse together during an intense battle, creating a new and powerful form. This new form has unique abilities and characteristics that the original Pokemon didn't have. The story could follow their adventures with this new form and how they are accepted or feared by others.
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.
In 'pokemon horror transformation fanfiction', the idea of a Pokemon's body mutating in grotesque ways can be really interesting. Maybe a Bulbasaur with its bulb growing out of control, sprouting thorny vines that seem to have a life of their own and lash out at anything nearby.
Another interesting concept is to write a fanfic about a group of Pokemon that form a secret society. They have their own rules and goals, and the story could follow a human or a Pokemon who stumbles upon this society and gets involved in their affairs.
One idea could be a fanfic where a trainer discovers a new and rare Pokemon species in an uncharted region. Another could be a story about a Pokemon that has unique abilities and how it changes the Pokemon battles in a particular area. Maybe a fanfic that focuses on the friendship between a trainer and a Pokemon that is usually considered difficult to train.
One idea could be that a trainer discovers a wounded Celebi. As the trainer nurses it back to health, Celebi, in a show of gratitude, temporarily transforms the trainer into a Pokemon to experience the world from their perspective. Another plot could involve Celebi using its transformation powers to save a group of Pokemon from a natural disaster by changing them into forms that can better survive the situation. For example, turning water - type Pokemon into flying - type Pokemon to escape rising floodwaters.
One idea could be a young trainer discovers an ancient spellbook that has pokemon transformation spells. He accidentally casts one on himself and turns into a Pikachu. Then he has to figure out how to reverse the spell while experiencing the world from a pokemon's perspective.
One idea could be a Vulpix that gets transformed into a different type of Pokemon due to a magical artifact. It then has to learn to adapt to its new form and abilities while trying to find a way to change back. Another plot could involve a trainer who accidentally causes the transformation of their Vulpix and they go on a journey together to figure out how to reverse it.
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.
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.
One idea could be a story about a trainer who discovers a rare lemon - colored Pokémon in a hidden grove. The Pokémon has unique abilities related to nature, like making lemon - scented plants grow rapidly. This could lead to an adventure where the trainer has to protect the Pokémon from poachers who want to sell it on the black market.
One interesting idea could be exploring the more scientific aspects of Pokémon. For example, how their powers might be related to real - world physics or biology. Another idea could be a more in - depth look at the Pokémon society, like their culture and economy. And also, perhaps a different take on the relationship between trainers and Pokémon, such as more equal partnerships rather than just the trainer being in control.