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.
Pikachu is a must - include. It's Ash's most iconic Pokemon. For Sawyer, his Slurpuff could be great. Also, Greninja for Ash would add a lot of action scenes. Sawyer's Sceptile could also be interesting to include as it can show the different training styles between them.
Tom Sawyer is the titular character, of course. He is a mischievous and adventurous boy. Another important character is Huckleberry Finn, Tom's friend who is more of a free spirit. Becky Thatcher is also a key character, she is Tom's love interest in the story.
Huck Finn is also likely to be an important character as he is often associated with Tom Sawyer in Mark Twain's works. In the context of a detective novel, he may assist Tom in his investigations or be involved in some way in the mystery.
Tom Sawyer is the main character, of course. He's a naughty but clever boy.
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.
Sawyer and Hazel are likely characters from a particular series, movie, or book that has a fan base. Without more context, it's hard to say exactly who they are. They could be from a lesser - known indie story or a popular mainstream franchise. But in the context of this fanfiction, they are the two main characters who are about to experience the journey of pregnancy together.
Maybe Danny is a kind - hearted guy, perhaps a musician or an artist, and Sawyer is a strong - willed woman, could be a journalist or a teacher. In the fanfiction, their personalities and backgrounds play important roles in how they handle the situation of Sawyer being pregnant. Their relationship could be a long - standing friendship that turns into something more because of the pregnancy.
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, 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.