He could have a Froakie. It's a common and cute starter in Kalos. Maybe also a Skiddo for traveling across the Kalos landscapes. And a Bunnelby would be a nice addition for its digging abilities.
One great aspect of 'Pokemon Ash in Kalos Fanfiction' is the new adventures it presents. Ash's journey in the Kalos region in fanfiction often has unique twists. For example, the fanfic writers might introduce new Pokemon that Ash befriends in ways different from the original series. It also allows for different character developments, like Ash becoming more strategic in battles.
There's also a fanfiction called 'Ash in Kalos: A New Beginning'. This one focuses on Ash arriving in Kalos and how he adapts to the new region. It has some great character development for Ash, as well as for his Pokemon. The story is well - written and has some interesting takes on the Kalos gym battles.
I would recommend 'Ash's Kalos Adventure Redefined'. It has a great plot where Ash discovers a hidden power within one of his Pokemon. It's really engaging.
In this fanfiction, Ash and May could be on separate adventures in Kalos at first. But then, they cross paths when they both get involved in a mystery related to a rare and powerful Pokémon in Kalos. They have to put their heads together, along with their Pokémon, to solve the mystery and protect the Pokémon from those who would use it for bad purposes.
One possible story could be that Ash and Dawn meet in Kalos and decide to team up for a Pokemon tournament. They bring their unique skills and Pokemon from their respective regions and face many challenges along the way, like dealing with tough opponents and adapting to the new Kalos Pokemon.
One possible strongest team could be Pikachu, Charizard, Greninja, Lucario, Sceptile, and Infernape. Pikachu has been with Ash since the start and has a strong bond. Charizard is extremely powerful. Greninja has its unique form and great combat skills. Lucario is a very capable fighter. Sceptile was a strong addition to Ash's team in Hoenn. And Infernape showed great power in Sinnoh.
There might be a fanfiction where Ash teams up with some unexpected trainers in the Kalos League. They combine their strategies and Pokemon to take on tough opponents. For example, he could partner with a trainer who specializes in Fairy - type Pokemon, which are quite prominent in Kalos. This could lead to some really creative battle scenarios and character interactions.
Well, it's popular because Ash is a beloved character. Fans are always interested in seeing more of his story, especially in a new region like Kalos. The fanfictions often explore his relationships with new friends and Pokemon in Kalos. They can also delve deeper into his growth as a trainer, which is something that the official series might not fully explore. For example, some fanfictions might show Ash's struggle with new battle strategies in Kalos in more detail than the anime. And the Kalos region itself offers a lot of inspiration with its fashion, culture, and unique Pokemon species.