The fanfic could be about Pikachu getting angry when a new powerful Pokemon arrives in the area and starts bullying the other Pokemon. Pikachu, being the brave little Pokemon it is, stands up to the bully. At first, it loses battles due to its anger getting the best of it. But with the support of its friends, it manages to channel its anger into strength and defeats the bully.
First, understand Pikachu's character. Pikachu is usually cute and friendly, so for it to be angry, there needs to be a strong reason. It could be something like unfair treatment. Then, build a vivid setting. For example, if it's angry because of a polluted environment, describe the dirty and harmful surroundings. Also, give it a goal while it's angry, like cleaning up the environment or teaching the polluters a lesson.
One possible plot could be that Mimikyu is jealous of Pikachu's popularity. However, instead of becoming enemies, they end up in a situation where they have to rely on each other. For example, they get lost in a strange part of the Pokemon world. Through this experience, Mimikyu realizes that popularity isn't everything and Pikachu learns to see Mimikyu's true value.
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.
Well, it could be a story of rivalry at first. Pikachu is quite popular among trainers and other Pokemon, while Mimikyu is often overlooked or feared. Mimikyu might envy Pikachu's status and decide to challenge it to battles. But during these battles, they start to understand each other better. Pikachu realizes that Mimikyu is just lonely and wants some attention. So instead of fighting, they end up working together to help other Pokemon in need. For example, they might save a group of Pichu from a landslide by using their combined electric powers.
One possible plot could be that Pikachu is exposed to a rare type of thunderstone during a powerful thunderstorm. This thunderstone has been charged with an ancient energy. Pikachu absorbs this energy and begins to evolve. But instead of evolving into Raichu right away, it goes through a series of strange and new intermediate forms, each with unique powers. As it evolves, Pikachu has to learn to control these new powers while also facing challenges from other Pokemon who are either jealous or see it as a threat.
One idea could be that the female Pikachu has unique electric powers that no other Pikachu has. She could go on a journey to discover the origin of these powers, facing various challenges along the way, like battles with powerful Pokemon and difficult terrains.
One possible plot could be that Pikachu is exposed to a rare form of electric energy in a thunderstorm that's charged with some mysterious power. This could start the evolution process. It might struggle at first, not understanding the changes its body is going through. As it evolves, it could gain new abilities like enhanced speed and a more powerful electric attack. And it might have to face new challenges in battles, as opponents are now more cautious of it.
One possibility could be that Serena gets angry when she is constantly overshadowed by other trainers in a big tournament. She might feel that all her hard work is being ignored, so she gets angry and decides to train even harder in isolation to prove herself.
One possible plot twist could be that Bayleef suddenly loses its ability to use grass - type moves. This would put both it and Pikachu in a difficult situation as they rely on Bayleef's moves in battles. They would then have to find a way to regain Bayleef's power, perhaps by going on a quest to find a special herb or meet a certain Pokemon that can help.
Well, perhaps Ash starts to idolize Pikachu after seeing its unique powers in a battle. He might try to imitate Pikachu's moves and even start collecting Pikachu - themed items.