Well, it could be a young and ambitious trainer who is just starting out on their Pokemon journey and has a layover at Mistralton Airport. Another main character might be an experienced trainer who gives advice to the newbie at the airport.
There might be a Pokemon ranger as a main character in the Mistralton Airport Pokemon fanfiction. The ranger is at the airport to make sure that all the Pokemon are in order and not causing any trouble. Also, a mysterious Pokemon trainer with a powerful and rare Pokemon could be one of the main characters. This trainer's presence at the airport might attract a lot of attention and even some envy from other trainers.
One interesting story could be about a trainer who discovers a rare Pokemon at Mistralton Airport. Maybe it's a Pokemon that's not native to the area and has been lost. The trainer then has to figure out how to take care of it and get it back to its proper place.
Given the lack of information about the 'fa airport fantasy story', it's difficult to determine the main characters. But in a typical airport - fantasy story scenario, there could be a group of friends who are on a journey together and get separated at the airport, only to find themselves in different parts of a magical airport world. Another possible main character could be a pilot who discovers something extraordinary while flying in or out of the airport. Or it could be a child who has a vivid imagination and sees things that others don't in the airport, like hidden doorways to other dimensions.
Obviously, Ash is one of the main characters. Since it's about him being a legendary Pokemon in this fanfiction, he's central to the story.
Obviously, Nyssa is a main character. She is likely to be the central focus of the story, driving the plot forward with her actions and decisions. Another main character could be her first Pokemon, which she has a special bond with. This Pokemon might be her constant companion throughout her adventures.
There might be other trainers in the fanfiction. They could be friends or rivals to Elaine. A rival trainer could constantly challenge Elaine to battles, pushing her to improve. And her friends could join her on adventures and offer support when she faces difficulties.
Obviously, Sawyer is a main character. But there could also be his Pokemon as important characters. Depending on the story, other trainers he meets during his journey might also be main characters. For example, if it's a story about a big tournament, the opponents he faces could be main characters too.
Obviously, Nate is a main character. His Pokemon are also important characters in the fanfiction. Depending on the story, there might be other trainers that Nate meets during his journey, like a rival trainer who constantly challenges him.
Well, obviously Fennel is one of the main characters. She is often the center of the story due to her role as a researcher. Sometimes, the main character from the Pokemon games might also be a main character in the fanfiction, interacting with Fennel and helping her with her research or getting help from her in their own Pokemon journey.
I'm not sure specifically as it depends on the particular fanfiction. It could be a young trainer with a special dragon - type Pokemon like a Charizard or Dragonite.
Another possible main character in the fanfiction could be a Pokemon that has a special connection with Conway. Let's say it's a Pikachu that has some unique abilities. This Pikachu might have been abandoned by its previous trainer and Conway takes it in. Their relationship then becomes a central part of the story, with the Pikachu helping Conway in battles and Conway protecting the Pikachu from danger.