One possible plot could be that Ash gets caught in a strange situation where a Hypno uses its powers on Pikachu to make it disobey Ash. Ash then has to find a way to break the hypnosis and regain Pikachu's loyalty. Maybe he teams up with some other Pokémon or trainers he meets along the way.
The main antagonist could be a rogue Pokémon trainer who has a special Hypno that has been enhanced to have this 'L to obey' power. This trainer might want to use this power to take over Pokémon battles and tournaments, so Ash has to stop him.
One possible fanfiction could involve Team Rocket using a new device to hypnotize Ash Ketchum. They might make him do silly things like singing a Pokémon theme song in a really strange voice or making Pikachu do a little dance. But of course, his friends would eventually figure out what's going on and try to break the hypnosis.
One possible fanfiction could be where a powerful Pokémon trainer with psychic abilities hypnotizes Ash Ketchum. In this story, the trainer might have an evil plan to use Ash to steal rare Pokémon. Ash, under the hypnosis, starts to obey commands against his will. However, his Pikachu senses something is wrong and tries to break the hypnosis by using its electric shocks on Ash at just the right moment. Eventually, Ash breaks free and battles the evil trainer.
Well, this type of fanfiction concept often delves into the realm of the psychological. The idea of mind control over Ash Ketchum can be seen as a way to play with power dynamics. If a villain is the one controlling him, it gives the villain an upper hand in a different way compared to just physical strength. And it forces the fanfiction writer to think about how the Pokémon world's rules and magic could be bent or used in relation to hypnosis. Also, it can open up opportunities for exploring different moral and ethical questions within the story, like whether it's right to use mind control, and how far his friends should go to free him.
Well, if Ash was hypnotized to obey commands in fanfiction, it might change the whole dynamic of his adventures. For example, Team Rocket could get hold of the hypnosis method and try to make Ash work for them. But Ash being Ash, even under hypnosis, his love for Pokémon might break through the commands and he could end up turning the situation around on Team Rocket.
The plot could involve a new and powerful villain who discovers a way to hypnotize Ash. This villain might want to use Ash's skills and knowledge of Pokémon to achieve their own evil goals, like stealing rare Pokémon or taking over a Pokémon gym. Ash, under the mind control, starts to obey the villain's commands without question, which alarms his friends. His Pokémon might sense something is wrong and try to resist following Ash's now - controlled commands.
It could have a huge impact. His Pokémon journey might take some strange turns. He could be sent on quests by the hypnotist that have nothing to do with his original goals. His Pokémon might have to adapt to following these new, strange commands from Ash who is under hypnosis.
One common theme is the struggle between the hypnotized Ash and his true self. His friends often play a crucial role in trying to break the hypnosis and bring him back to normal. Another theme could be the power struggle between the one who hypnotizes Ash and those who want to free him.
Maybe a new, mysterious villain who has a grudge against Ash or wants to use his skills for their own evil purposes. This villain might be from a far - off region and has special powers that allow them to hypnotize people. They see Ash as a useful tool to carry out their plans in the Pokémon world.