Well, aside from Serena, there could be other Kalos characters like Diantha. Since she is the champion of Kalos, her interaction with Ash could be an interesting addition to the harem concept. Then there are the various female trainers that Ash meets during his battles and travels in Kalos, any of them could potentially be part of the harem.
Serena could be one of the main characters in the harem. She has a close relationship with Ash already in the original series. Also, Miette might be included as she showed interest in Ash. And Shauna could also be part of it as she was always friendly towards Ash during his Kalos journey.
Definitely Serena as she has feelings for Ash. Then there could be some minor characters like Alexa, the journalist. She could be part of the harem as she might be intrigued by Ash's adventures in Kalos. And don't forget about the female rivals that Ash faces, they could also end up in the harem due to their respect and admiration for him over time.
He could meet Serena, who might be his travel companion or a friendly rival. Also, Clemont and Bonnie are likely characters he'd encounter. They could help Ash with his journey in Kalos, like Clemont with his inventions and Bonnie with her cheerful nature.
In Kalos, one potential rival for Ash could be a local trainer who specializes in Fairy - type Pokémon. Fairy - type Pokémon can be quite tricky in battles, and this trainer has mastered the use of their unique abilities. For Misty, a rival could be a girl who is an expert in water - type Pokémon battles, just like Misty herself. This girl might have some rare water - type Pokémon from Kalos that Misty has never seen before.
He could interact with Serena again. Since they have a history in Kalos, they might have new adventures together. Also, Clemont and Bonnie are likely characters he would meet up with. They could continue their friendship and maybe work on some new inventions together with Clemont, or have fun times with Bonnie and her love for Pokémon.
Serena is a very common character. She has a pre - existing relationship with Ash from the anime and is often a central part of the harem in these fanfictions. Another one is Miette. She is competitive and her interactions with Ash can add an interesting dynamic to the story. Bonnie is also sometimes included. Her innocent and curious nature can bring a different flavor to the harem, especially with her love for Pokémon and her dreams of becoming a Pokémon trainer like Ash.
In the 'smart ash in kalos fanfiction', Ash is surely one of the main characters as the title implies. His Pokémon, like Pikachu, Greninja, etc., would also be important characters. And perhaps some of the friends he makes in the Kalos region, like Serena, Clemont, and Bonnie, would be main characters as well. They could interact with this'smart Ash' in different ways, with Serena maybe being attracted to his newfound intelligence or Clemont being impressed and wanting to learn from him.
Obviously, Ash would be one of the main characters. There might also be his Pokémon like Pikachu. And he could meet new friends in Kalos like Serena, who often accompanies Ash in the official Kalos storyline.
Well, obviously Ash is one of the main characters. His Pokémon are also key characters in these fanfictions. They are the ones that show his strength through battles.
Definitely Misty could be one. She has a long - standing relationship with Ash and might be part of the harem as she still has feelings for him. Another could be Serena, who has shown strong romantic interest in Ash in the past. Dawn might also be a character, as she and Ash have a great friendship that could potentially turn into more in a harem - like scenario.
The main characters are Ash and Red. Ash, who has been traveling through different regions in the Pokémon world, and Red, who has his own legend in the Pokémon games. In a Kalos - themed fanfiction, they will be the ones driving the story forward. They may encounter other trainers, Gym Leaders, or even Team Flare members, but it's their actions and decisions that will shape the narrative.
Obviously, Ash himself. And his Kalos friends like Serena would probably be there. Clemont and Bonnie might also make an appearance as they were important parts of Ash's Kalos journey.