It could be a new, young Pokemon who befriends the old Pikachu. This young Pokemon could witness Pikachu's decline and death, and through this experience, learn about the history and importance of Pikachu in the Pokemon world.
The fanfiction could be about how the Pokemon world has changed over time and Pikachu is left behind as an 'old - fashioned' Pokemon. It might face discrimination or neglect because of its age. The death of Pikachu could be a symbol of the end of an era in the Pokemon world. It could also explore how the younger generation of Pokemon and trainers view Pikachu's legacy.
Well, it depends. While Pikachu is an old and well - known Pokemon in the franchise, in fanfiction, it doesn't necessarily mean it's 'too old'. Some fanfiction writers might use Pikachu's long - established character as a base to build new and unique stories. They could explore different aspects of Pikachu's personality, like its loyalty or its mischievous side in more depth. Or they could create alternate universes where Pikachu has different abilities or relationships. So, just because it's been around a long time doesn't automatically make it too old for fanfiction.
The repetitive storylines. So many stories about Pikachu follow the same pattern: it gets caught by a trainer, battles other Pokemon, and levels up. In fanfiction, this lack of originality can make Pikachu seem old. Writers often find it difficult to break away from these established story patterns, which in turn makes the character seem stale.
It could be a Pokemon itself. Maybe a dark - type Pokemon with a grudge against humans and Pikachu in particular. This Pokemon could be using its powers to cause chaos in the city, and Pikachu has to figure out its motives and stop it before it's too late.
It could be a trainer who hates Pikachu and wants to capture all of them. This would put Ash, as a Pikachu fan, in direct conflict with this trainer.
Another possibility is a rival trainer who has a Pokemon that is weak against Raichu. This trainer might try to prevent Pikachu from evolving to keep their own Pokemon's advantage in battles. They could try to steal Pikachu's food or training resources to slow down its growth and evolution.
A group of Team Rocket - like villains could be the main antagonists. They might want to capture Pikachu while it's in the process of evolving because they believe that an evolving Pikachu would have some special power that they could use for their evil plans. They constantly try to disrupt Pikachu's evolution and the bond between Pikachu and its trainer.
Often, in addition to Eevee and Pikachu, their trainers might also be important characters. The trainers' actions and decisions can influence what Eevee and Pikachu do. For instance, if the trainer sends them on a mission, that becomes the basis of the adventure in the fanfiction. Also, sometimes other Pokémon that are friends with Eevee and Pikachu, like Charmander or Squirtle, might make appearances and play secondary roles in the story.
There could also be other characters that play important roles. For example, some of Ash's friends from the Pokemon series like Misty or Brock might make appearances in the fanfiction. They could offer support or advice to Ash during his adventures with Pikachu.
A powerful and corrupted Gengar could be a great antagonist. Gengar could use its ghost - type powers to create illusions and traps within the mystery dungeon, making it difficult for Pikachu and its friends to progress. It might be after a powerful artifact hidden in the dungeon and will stop at nothing to get it.