Another character that can be popular is Professor Oak. He is often included as a mentor figure. He might give advice to Ashley and Gary, or he could be the one to send them on a special mission that drives the plot of the fanfiction.
Obviously Ashley and Gary are very popular. They are often the focus of these fanfictions. Their dynamic, whether it's as rivals or friends, is really interesting to fans.
One plot idea could be that Ashley and Gary team up to compete in a special Pokemon tournament that has unique rules. They have to combine their different training styles to succeed.
Professor Oak could also be a good pairing. Gary could learn more about Pokemon research from his grandfather, and they could have adventures together in search of new Pokemon species or to study Pokemon behavior.
One great 'pokemon ashley x gary fanfiction' story is 'The Unlikely Bond'. It shows their journey together in the pokemon world, with unique character development. Another is 'Ashley and Gary's Adventure', which focuses on their adventures while facing challenges side by side. There's also 'A New Chapter for Ashley and Gary' that delves into their relationship evolving in unexpected ways.
I think Gary would be a great addition. His rivalry with Ash could create some interesting storylines. He might start off as a bit of a antagonist but then end up being an ally. Also, Dawn could be included. She has her own unique style of training Pokemon and her friendship with Ash could be further explored in the context of Ashley being there as well. And then there's May, who could bring in her Contest experiences and help Ash and Ashley in different ways related to Pokemon showcases.
Gary is another character that stands out. He might be the rival who is always one step behind Ash in terms of popularity but is constantly trying to up his game. He could be part of the advanced Pokemon training class and is known for his vast knowledge of different Pokemon species.
Squirtle is very popular. Since it has water - based abilities, it can easily be related to the ink - based battles in Splatoon. It could be a key character in a story where Pokemon and Splatoon characters team up for a water - ink related mission. Also, the main Inkling characters from Splatoon, like Agent 3 or Agent 4, are popular as they are the main representatives of the Splatoon world. They can be shown as having adventures in the Pokemon world, learning about Pokemon training and sharing their ink - fighting techniques with the trainers there.
The player character themselves are often very popular. Since every player can customize their trainer in the game, it gives a lot of room for creativity in fanfiction.
Pikachu is often very popular. Its cute appearance and electric - based abilities can be used in many humorous situations. Also, Team Rocket's Jessie, James and Meowth are popular as they are always getting into comical scrapes while trying to steal Pokemon.
Some original characters created by fanfiction writers can also gain popularity. For example, a young trainer who starts their journey in the Pokemon Red world with a big dream but has to face many difficulties. Their growth and development throughout the story can attract a lot of readers.
Mewtwo is another favorite. Given its psychic powers and origin story of being a genetically created Pokemon, it can be a key figure in battles. It could be fighting for the rights of all Pokemon or be manipulated by the wrong side due to its power.