The main characters could be popular pokemon girls like Misty. Since she's feisty and determined, her being involved in a hypno - related story could be really interesting. Another could be Serena, as she's always evolving in her journey and a hypno situation could be a new twist for her character development.
For the 'pokemon girls hypno fanfiction', May could be a main character. She's known for her growth as a trainer. Hypno - influenced events could test her skills and her relationships with her pokemon in new ways. And then there's Bianca. Her somewhat clumsy yet endearing nature could bring a different flavor to the story when combined with the hypno element.
Hypno is obviously a key character in this fanfiction. There could also be other Pokemon that are affected by Hypno's zapper. For instance, Pikachu might be zapped and then has some sort of unique reaction. And there could be a villainous character who wants to steal Hypno's zapper for their own evil plans.
Often, the trainer is a main character. They are the ones who interact with Hypno, whether it's trying to catch it, train it, or go on adventures with it.
Gengar could be an interesting addition to the team with Hypno. Although Gengar is a Ghost/Poison - type, it has a mischievous nature that could complement Hypno's more serious demeanor. Gengar could use its sneaky abilities to set up traps for opponents, and Hypno could then use its psychic powers to finish them off when they're caught in the trap.
Most likely Naruto would be one of the main characters since it's in the 'naruto' fanfiction. Others could be his friends like Sasuke or Sakura who might be involved in the story related to the hypno gun.
One idea could be that a hypno pokemon accidentally hypnotizes a group of pokemon girls, causing them to believe they are on a grand adventure in a different pokemon region. They start exploring areas that are usually off - limits and encounter rare pokemon. Another could be that a trainer uses a hypno - influenced device to make the pokemon girls see their pokemon in a new, super - powered way, which changes their battle strategies.
A young and ambitious Pokemon trainer who wants to save their injured Pokemon through surgery could be a main character. Also, the Pokemon doctor who is an expert in performing these surgeries.
I really can't be certain about the main characters without more details. However, it's possible that in addition to the hypno girl, there are other characters in her community. Maybe there's a boy who is in love with her and has to deal with her hypnotic nature. Or there could be a group of scientists who are interested in studying her unique ability.
Team Rocket could also be the focus of a reunion fanfiction. Maybe they've reformed and are having a reunion to celebrate their new lives away from their villainous ways. They could be showing off their new Pokemon or skills that they've developed.
The main characters could be a young, inexperienced trainer who has just caught their first Fire - type and Ice - type Pokemon. As they journey through the Pokemon regions, they learn about the strengths and weaknesses of their Pokemon, and grow as a trainer. Along the way, they meet other trainers and Pokemon that help or hinder their progress. For example, an older, more experienced trainer who tries to convince the young trainer to give up their Ice - type Pokemon because it's 'too weak' in their opinion.
I think Misty from the Pokemon world could be a main character in this fanfiction. Since she has a connection with water - type Pokemon, she could easily fit into the underwater world of The Little Mermaid. Along with her, a Psyduck would be there. Psyduck's clumsy yet powerful abilities could add an interesting element to the story. And of course, Ariel would be a main character. She could learn a lot from Misty about the Pokemon world and they could team up to protect both their worlds from any threats.