Perhaps a fanfic where a trainer's Eevee evolves into different forms at will due to a strange encounter in an ancient forest. This Eevee then uses its unique ability to help other pokemon in distress, and the story could follow their adventures across the pokemon world. It could involve a lot of exploration of different areas and interactions with various pokemon species.
A really cool plot could be a 'pokemon slash fanfic' set in a post - apocalyptic pokemon world. Some pokemon have developed strange new abilities because of the changed environment. A group of misfit pokemon, like a Meowth, a Squirtle, and a Bulbasaur, must band together to find a way to restore the world to its former state. They face many challenges along the way, including battling against other pokemon who have been corrupted by the new conditions.
A great plot could involve a world where Skin Pokemon are the outcasts because their changing abilities are seen as untrustworthy. A group of trainers decides to prove that Skin Pokemon are just as loyal and worthy as any other type. They form a sort of rescue team for Skin Pokemon in danger and work towards changing the perception of these unique creatures in the Pokemon world.
Well, a plot could revolve around Janine being involved in a Pokemon tournament where she uses her unique Poison - type Pokemon in unexpected ways. She might face some opponents who underestimate her because of her small stature but she proves them wrong with her brilliant strategies. Or perhaps a story where Janine discovers an ancient Pokemon artifact that has the power to control all Poison - type Pokemon and she has to protect it from evil forces.
One idea could be a baby Pokemon getting lost while wearing diapers and the other Pokemon in the area have to help it find its way back home. Another could be a trainer who discovers a rare Pokemon in diapers and has to figure out how to take care of it while also protecting it from those who might want to steal it for its rarity.
One idea could be a trainer in the Pokemon Sumo world who discovers a rare Pokemon with unique sumo - like abilities. Another could be a Pokemon sumo tournament where the underdog Pokemon rises to victory. Or perhaps a story about a trainer who has to train their Pokemon specifically for sumo battles in a new region.
One idea could be exploring the backstory of how Professor Oak started his research on Pokemon. Maybe he had a special encounter as a young trainer that inspired him to study Pokemon evolution and behavior.
One idea could be to focus on a trainer who discovers a rare and powerful Pokemon that no one has ever seen before in the Unova region. They then have to protect it from evil organizations who want to use it for their own gain.
One idea could be to focus on an underrated Pokemon's journey. For example, a Sentret that has big dreams of becoming a strong protector in the forest. It could face challenges like dealing with a group of mischievous Poochyena.
One idea could be a story about a trainer who discovers a rare and powerful Pokemon in Pokemon Home that has been lost in time. They then have to protect it from various villains who want to use its power for evil.
Another interesting plot could be that the main character's Pokemon start to develop strange behaviors. It turns out that there is a mysterious force in the region that is affecting their minds. The character has to embark on a journey to find the source of this force and stop it before it causes chaos among all Pokemon.
One idea could be a trainer who enters the Pokemon Rodeo with an underdog Pokemon. They work together to overcome the odds and win the competition. For example, a trainer with a Pichu, which is small but has great potential. Through training and building a strong bond, they surprise everyone in the Rodeo.