No, it's not ethical. Fanfiction often draws on existing concepts from the Pokemon universe, but this idea crosses a line. We have to consider the implications of such a concept. It can be disturbing and goes against the normal understanding of relationships between species. Even in the realm of fictional and creative works, there are moral boundaries that should not be crossed.
Some fanfictions focus on the love stories that can occur when Pokemon turn into humans. For instance, a Pikachu - turned - human might fall in love with a human trainer. But they face difficulties because of their unique situation. They have to hide their true identity from the public while also dealing with their own insecurities about being different.
Another concept could be related to evolution. Just as Pokemon evolve in their natural forms, what if there was a new kind of evolution that turned them into humans? It could be a result of environmental changes or a new type of energy that forces them to adapt in this extreme way. For example, if their natural habitats are being destroyed, they might evolve into a form that can better survive in the human - dominated world.
Ash is obviously one of the main characters. He is at the center of the harem concept. Then there would likely be a group of human characters who are part of his harem, though their specific identities can vary greatly depending on the fanfiction.
One challenge is communication. If they are turned into a Pokémon that doesn't have a human - like language ability, it would be hard to convey their thoughts and needs. Another challenge is adapting to a new physical form. For example, if they become a flying - type Pokémon, they have to learn how to fly which is completely new to them as humans. Also, they may face danger from other Pokémon who see them as either prey or competition.
One interesting idea could be exploring the relationships between Pokemon and humans in a more in - depth way, like a human having a telepathic bond with their Pokemon. Another is imagining a world where humans can transform into Pokemon temporarily for certain tasks or battles.
By exploring their past as Pokemon. If a Bulbasaur - turned - human had a tough life in the wild as a Pokemon, that could shape their human personality. Maybe they'd be more cautious or have a strong survival instinct.
One interesting concept could be the transformation of Pokemon abilities into human skills. For example, a Pikachu as a human might have the ability to generate electricity in a more controlled and unique way within the human world. Another concept could be the Pokemon-human hybrids that inherit both the physical and mental traits of Pokemon and humans, leading to complex and diverse characters.
Ash is often a popular character in such fanfictions. Since he has a long - standing relationship with many pokemon in the original series, it's easy to imagine new stories where his bond with pokemon takes on new dimensions when meeting humans in different situations.
One famous story is 'The Metamorphosis' by Franz Kafka. In it, the main character Gregor Samsa wakes up one day transformed into a giant insect. This story explores themes of alienation and the human condition in a very unique way.