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.
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.
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.
One possible plot could be that a villain uses hypnosis on Ash Ketchum to make him do their bidding in Pokémon battles. So instead of using his own strategies, he's forced to follow the commands of the hypnotist. This would create a lot of chaos and challenges for his friends as they try to figure out what's wrong with Ash and how to break the hypnosis.
The plot could be that an unknown villain hypnotizes Ash. The villain wants to use Ash's skills and reputation to steal Pokémon. Ash, under hypnosis, starts to lead other trainers into traps. His friends are confused at first but then realize he's not himself. They search for a way to reverse the hypnosis, perhaps by finding a rare Pokémon or a special item.
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.
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.
Maybe a rogue Pokémon trainer who has a grudge against Ash. This trainer has dabbled in some dark and forbidden Pokémon training techniques that allow them to control minds. They target Ash because he represents everything they are not - kind, successful, and loved by many Pokémon.
Well, the concept of Ash having to obey is interesting because it can completely change the dynamics of his relationships. His Pokémon, his friends, and his rivals will all interact with him differently. It also allows the author to explore different plotlines and scenarios that wouldn't be possible in the normal Pokémon storyline where Ash is more independent.
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.