An isolated island where a group of researchers were conducting experiments on Pokemon that went horribly wrong. The desolate beaches, the dilapidated research facilities, and the sense of being cut off from the rest of the world all contribute to the horror. The transformed Pokemon on this island are not only a threat but also a reminder of the failed experiment and the unknown consequences that are now running wild.
One interesting idea could be a Pokemon that has been corrupted by a dark force and starts to hunt other Pokemon and trainers. For example, a Pikachu with red, glowing eyes instead of its normal cute ones, and it uses its electric powers in a more menacing way.
In a particular Pokemon horror story fanfiction, a young trainer discovers a strange Pokeball. When he catches a Pokemon with it, the Pokemon slowly drains his life force. As it turns out, the Pokeball was created by an evil organization to capture trainers' souls through their Pokemon. The trainer has to find a way to free his Pokemon and break the connection before it's too late. There are also fanfictions that involve a Pokemon evolving in a wrong and grotesque way, like a Charmander evolving into a monster - like creature instead of a Charmeleon, which brings chaos and horror to the surrounding area.
Gengar is quite popular. It already has a spooky look with its shadowy form and mischievous nature in the regular Pokemon lore, so it's easy to make it even more terrifying in horror fanfic. Another one is Banette. It's a Pokemon that is said to be created from a discarded doll, which is already a creepy concept. In horror fanfic, it can be made to have even more vengeful and dangerous tendencies. Misdreavus is also a common one. Its floating, ghost - like appearance and the fact that it likes to play tricks on people can be amplified in horror stories to make it a really menacing presence.
Another aspect is the relationships between the Pokemon. In normal Pokemon stories, they support and work together in a positive way. However, in horror fanfiction, the stress and horror can put a strain on those relationships. There could be suspicion among them, or one Pokemon might be possessed and turn on its friends. This exploration of how the horror affects the social fabric of the Pokemon world is something that gives Pokemon Mystery Dungeon horror fanfiction its own identity.
In 'pokemon horror transformation fanfiction', the idea of a Pokemon's body mutating in grotesque ways can be really interesting. Maybe a Bulbasaur with its bulb growing out of control, sprouting thorny vines that seem to have a life of their own and lash out at anything nearby.
Gengar is a popular choice. Its already spooky appearance and ghost - type nature make it easy to incorporate into horror scenarios. It can lurk in the shadows, play tricks on trainers, or even possess other Pokemon to cause chaos.
Once, a trainer was exploring an abandoned Pokemon Mansion. As he walked through the dark corridors, his Pokeballs started to shake violently on their own. His Pikachu, usually so brave, cowered in fear. Out of the shadows, a strange, distorted Gengar emerged. Its eyes glowed red with an evil intent. The trainer tried to run but his feet felt like they were glued to the floor. The Gengar let out a terrifying laugh that echoed throughout the mansion, and the trainer knew he was in for a very bad time.
They're popular because it's a unique twist on the usually positive and family - friendly Pokemon franchise. It adds an element of mystery and danger that's different from the regular Pokemon adventures.
One common theme is the loss of self. When Ash transforms in horror fanfiction, he might start to lose his identity as a trainer. For example, he could become more like the Pokemon he transforms into, forgetting his goals and friends. Another theme is the fear of the unknown. The transformation process itself is often mysterious and unpredictable, creating a sense of horror. Also, there can be themes related to being an outcast. Since his transformation is abnormal, Ash might be shunned by his friends or society in the fanfiction.