There could be a competitive aspect. They might compete for the attention of a trainer or for a particular resource in the Pokemon world. For instance, a rare berry that only grows in a certain area. Their interactions during this competition could range from playful taunts to more serious showdowns. However, through this competition, they could also learn to respect each other's abilities.
The fanfic could be about Mimikyu being jealous of Pikachu's popularity. Since Pikachu is so well - loved, Mimikyu might try to outshine it in some comical ways. For example, Mimikyu could enter a Pokemon contest where Pikachu is also participating and use its unique disguise abilities to create some chaos and unexpected turns during the competition.
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.
Well, it could be about Pikachu befriending Mimikyu. Maybe Pikachu discovers that Mimikyu is not as scary as it looks under that disguise. They could go on adventures together in the Pokemon world, like exploring a new forest or finding a rare Pokemon.
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.
For Pikachu, remember it's energetic and friendly. It often shows its emotions through its electric shocks, like when it's excited or scared. Pikachu loves to play and is very loyal to its trainer. Mimikyu, on the other hand, is a bit more mysterious. It's shy because it's self - conscious about its appearance. It hides under its disguise. Mimikyu can be a bit envious at times but also has a big heart deep down.
Both of them could learn about the importance of individuality. Pikachu might realize that being different like Mimikyu is not a bad thing, and Mimikyu could understand that it doesn't have to be exactly like Pikachu to be accepted. They could both grow to appreciate their own unique qualities as well as those of each other.
One plot twist could be that Mimikyu's disguise is actually a magic spell that was cast on it by an evil Pokemon, and Pikachu has to find a way to break the spell.
Here's a plot idea. There's a new Pokemon trainer in town who only wants to catch Pikachu and Mimikyu. They keep running away from the trainer and end up in an old, abandoned Pokemon sanctuary. There, they find out about the history of the place and some secrets about their own species. They also meet some old and wise Pokemon who teach them new moves. Eventually, they outwit the trainer and decide to stay friends and protect the sanctuary from any harm in the future.
Mimikyu has the ability to create illusions. In the fanfic, it could use this ability to protect Pikachu. For example, when a powerful and dangerous Pokemon attacks them, Mimikyu could create an illusion of a much stronger Pokemon to scare it away. Pikachu's electric abilities could be used to power up Mimikyu's illusions, making them more realistic. They could also use their combined skills to solve puzzles. Say there's a maze that is protected by electric barriers. Pikachu could discharge electricity to temporarily disable the barriers while Mimikyu creates an illusion of the correct path for them to follow.