A more complex plot could involve Detective Pikachu trying to figure out a conspiracy among a group of humans who are trying to use Pokemon for illegal and unethical experiments. This would involve Pikachu teaming up with other Pokemon and human allies, like Tim, to expose the bad guys. They would have to face many obstacles and dangerous Pokemon controlled by the villains along the way.
Perhaps a story where Pikachu loses his memory but still has his detective skills intact. He starts to investigate his own past while also solving a current mystery in Ryme City. Along the journey, he rediscovers old friends and enemies, and uncovers secrets about his own origin.
A great idea for a Pokemon Detective Pikachu fanfic could be to set it in a different region. For example, a region that is mostly covered in ice. Pikachu and Tim would have to adapt to the new environment and the different types of Pokemon there. They could be investigating a series of disappearances of ice - type Pokemon. Maybe there's a secret underground lair where a powerful but misunderstood Pokemon is hiding and Pikachu has to use his detective skills to uncover the truth and save the day.
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.
One idea could be an OC who is a detective trainee and teams up with Detective Pikachu to solve a mystery in a new part of the Pokemon world. Maybe they are investigating a series of disappearances of rare Pokemon. Another plot could involve an OC with a special ability to communicate with certain types of Pokemon that Pikachu can't, and together they use their combined skills to stop a villain who wants to use these Pokemon for evil.
One idea could be to create an OC who is a detective from a different region, like Unova. They could have a unique Pokemon partner, like a Zorua that can transform and help with investigations in sneaky ways. Their backstory could involve coming to Ryme City to learn new detective techniques.
One idea could be that Pikachu wakes up in a strange part of the mystery dungeon with no memory of how it got there. It has to team up with other Pokemon it meets along the way, like a Charmander and a Squirtle, to figure out the mystery of the dungeon and also find a way to get back home.
A plot could revolve around Pikachu getting sick and Lillie using her knowledge of Pokémon care to nurse it back to health. During this time, they develop a deep friendship. Then, they notice some strange behavior in other Pokémon around them. Together, they start to investigate and find out that there is a pollution source affecting the Pokémon. Lillie and Pikachu then try to find a way to clean up the pollution and restore the health of the Pokémon in the area. This would show their caring and adventurous sides.
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 idea could be a story where Pikachu gets separated from the trainer in an unknown and dangerous area, like the mysterious depths of Viridian Forest. It has to find its way back while making new Pokemon friends and facing challenges from wild Pokemon.
Perhaps there could be a plot where Pikachu and Emolga enter a Pokémon - only talent show. Emolga wants to show off its flying skills, while Pikachu plans to use its electric attacks in a creative way. They have to practice hard and deal with some jealous Pokémon who try to sabotage them.
One idea could be that Pikachu and Glaceon go on an adventure in a magical forest. They encounter strange creatures and have to work together to overcome obstacles. For example, they might find a lost baby Pokémon and need to reunite it with its family. Another plot could be centered around a competition where they both participate and learn about each other's strengths and weaknesses during the process.