The main character is Ash. But in some versions of the fanfiction, there could be new characters introduced that are related to the situation he's in. For instance, a hermit who lives in the forest where Ash is stranded. This hermit could either help Ash or be a hindrance, adding more depth and complexity to the story.
Gary could be a likely character. He has always been Ash's rival and there could be a plot where his jealousy or some other motive leads him to betray Ash. Another could be one of his so - called friends from the Pokemon League who might be influenced by power or some dark secret. Or, in some really dark fanfictions, it could be a Pokemon that Ash trusted deeply but for some reason turns on him.
Ash might meet some lone Pokémon trainers. These trainers could be on their own quests, similar to Ash's. They might have unique Pokémon or training methods that Ash can learn from.
There could be a lone traveler who Ash meets while he is alone. This traveler might have a unique way of training Pokemon that Ash has never seen before and could teach him some new tricks.
He might meet some local Sinnoh trainers who are experts in training specific types of Pokémon, like a trainer who specializes in ice - type Pokémon in the colder regions of Sinnoh.
There might be a young and inexperienced trainer who is lost. Ash, being the more experienced one, decides to help the trainer find their way. This new character could look up to Ash and in the process, Ash learns more about himself as a role model. It would be an interesting dynamic as Ash is usually the one being guided by his friends.
The main character is likely Ash, as it's in the title 'ash trains alone fanfic'.
There could be a wise old hermit who lives in a secluded forest that Ash meets during his solo travels. This hermit might have a deep knowledge of Pokémon lore and give Ash some valuable advice.
I'm not sure as there isn't much information given. But it could be an ordinary person who has to face challenges alone.
Obviously, Ash is the central character. But there could also be his Pokémon partners, like Pikachu, who might have enhanced abilities or a deeper connection with Ash due to his godlike status. Other trainers like Misty and Brock could also be important, perhaps following Ash in his new godlike journey and learning from his newfound powers.
Ash is often seen as the more action - oriented of the two. He could be the one who has special skills like combat or magic in some fanfictions. Ashley, though, has her own charm. She may be good at making friends, which helps them in their adventures. Their relationship can range from being just friends to having romantic undertones, depending on the direction the fanfiction author takes.