One idea could be a Pikachu accidentally getting into the bath with its trainer and having a little adventure in the soapy water. It might discover some hidden toys at the bottom of the bath that it thinks are treasures.
In a Pokemon fanfiction for bath time fun, perhaps a water - type Pokemon like Squirtle could create little water bubbles and play games with them in the bath. The trainer could join in and try to pop the bubbles that Squirtle makes. It would be a really cute and fun scenario.
One idea could be that Pikachu accidentally slips into the bath while chasing a floating Pokeball. It creates electric sparks in the water which turn the bath water into a mini electric pool, but without harming anyone. The other Pokémon gather around to see the strange phenomenon and it becomes a fun bath time adventure.
One idea could be a magical bath time. In the fanfic, the character could discover that the bath water has special powers, like making them able to communicate with mythical creatures that live in the drain. For example, they might meet a tiny mermaid who gives them a pearl as a gift.
Maybe a Jigglypuff could be in the bathroom during bath time. It could start singing its sweet song, which makes the bath time even more relaxing for the trainer. Meanwhile, a Psyduck could be splashing around, not really understanding what's going on but still having a great time. And the trainer could be sharing some bath toys with these Pokemon.
By giving them unique bath - related quirks. For example, Meowth could be obsessed with keeping his fur perfectly groomed during bath time, using his claws as combs. This would make him an interesting character as he scolds the other Pokémon for splashing too much water and messing up his grooming session.
In a more elaborate fanfic, Misty enters a Pokémon - themed amusement park. There are rides and attractions, but one particular area has a tickle zone. Misty is dared by her friends to enter. Once inside, she is bombarded with all kinds of tickling mechanisms, from tickling feathers to gentle electrical tickles. She has to make her way through this zone to get to the prize at the end, which is a rare Pokémon item. Along the way, she discovers that the tickle zone was actually set up by a friendly Pokémon trainer as a test of courage and humor.
Maybe Marceline the Vampire Queen teams up with a Dark - type Pokémon in a fanfiction. Since she has a somewhat dark and mysterious personality, it would be interesting to see how she interacts with a Pokémon that shares those traits. For example, she could form a bond with a Umbreon and they could go on adventures together.
One interesting plot could be Naruto accidentally using a new jutsu in the bath that turns the water into a mini - ocean with sea creatures. Another could be Naruto having a heart - to - heart conversation with a summoned toad while in the bath, sharing his dreams and fears. Maybe there's a plot where Naruto discovers a hidden message on the bath tiles that leads him on a new adventure.
One interesting plot could be Ash traveling back to the time of the first Pokemon ever discovered. He could witness the origin of Pokemon-human relationships and perhaps influence how they evolved over time. Another idea is Ash traveling to a future time where Pokemon have developed new and strange abilities, and he has to adapt quickly to this new environment. Also, he could go back in time to prevent a great Pokemon disaster that was hinted at in the original series.
One idea could be a hybrid of Pikachu and Eevee. This hybrid could have the cute appearance of both, with Pikachu's lightning - based powers combined with Eevee's ability to evolve into different forms. It could be a central character in a story where it's trying to find its place in the Pokemon world, being different from the normal Pokemon.
One idea could be the main character being reborn as a Pikachu and having to navigate the world with its electric powers while making friends with other pokemon. Another could be being reborn as a Eevee and having the unique ability to evolve into any form at will, which causes both envy and admiration among other pokemon. Maybe the reborn pokemon has memories of being a human and uses that knowledge to outwit trainers and other threats.