Well, in such a fanfic, a cool plot point might be that Ash, as a Pikachu, has to communicate differently. Since he can't talk like a human anymore, he has to find new ways to convey his thoughts and ideas to his friends. Also, there could be a plot where he discovers new powers that normal Pikachu don't have because he was once human. For example, he might be able to strategize better than a regular Pikachu in battles.
One possible plot could be that Ash turns into Pikachu and has to learn how to communicate with his human friends in this new form. He might struggle at first, but then discovers that he can use his Pikachu abilities in unique ways to help the group in battles and in solving problems around them.
The way Ash adapts to Pikachu's instincts could be really interesting. He might find himself being more drawn to shiny objects or having an urge to store food in a certain way. And his relationship with his own Pikachu (if it still exists in the story) would be very different. They could become like equal partners instead of trainer - Pokémon.
One possible plot could be Pikachu getting influenced by a dark and powerful Pokemon. For example, a Darkrai might use its nightmare - inducing powers on Pikachu. This could make Pikachu start to attack other Pokemon and trainers without mercy. Maybe Pikachu would first target its own trainer, Ash, as it would be the most shocking turn of events. This would create a lot of chaos in the Pokemon world and force Ash and his other Pokemon friends to try and figure out how to save Pikachu from this evil state.
Team Rocket could still be the main antagonists. They might see Ash as a Pikachu and try to capture him more than ever, thinking he's a special Pikachu. Maybe they believe he has some sort of new power because of his transformation.
One idea could be that Pikachu suddenly loses its electric powers and Ash has to find a way to help it regain them. This could involve a journey to a mysterious place that is said to have the power to restore Pokemon abilities.
Well, one interesting plot point could be Ash facing extremely tough opponents that he has never encountered before. This would test his skills and strategies to the limit. Another might be Ash making unexpected alliances with other trainers or even some Pokemon. It could also be that he discovers a new type of Pokemon evolution that changes the game in his journey to become a Pokemon master.
Well, one possible plot line could be Ash and Pikachu getting lost in a mysterious forest in the fanfiction. They might encounter rare and powerful Pokemon that they've never seen before. This could lead to Ash having to come up with new strategies to either befriend or battle these Pokemon, all while relying on Pikachu's unique abilities.
Well, it could start with Ash being transformed into a Pikachu in a mysterious forest. His friends are initially confused but soon realize it's him. As a Pikachu, Ash discovers new abilities he didn't know about before. He might be able to sense things like incoming danger more acutely. He could also have a hard time convincing his other Pokémon that he is still their trainer. Throughout the fanfiction, there could be a series of comical and exciting events as he tries to adapt to his new form and find a way to reverse the transformation.
The plot might involve Ash, as a female, trying to find her place in the Pokemon league again. Since she has a new form, she might have to re - establish her reputation. She could form new alliances with other trainers who see her in a different light. For example, some male trainers might be more protective or some female trainers might be more competitive towards her. And along the way, she discovers new abilities or a different connection with her Pokemon that was hidden before the transformation.
One idea could be that the female Pikachu has a special power that only Ash can help her control. For example, she might be able to communicate with a certain type of Pokémon that is usually very difficult to reach. Ash, with his experience and kind heart, guides her in using this power for good, like helping to resolve a conflict between different Pokémon groups in a forest.