Maybe it's an older, more experienced athlete from a different magical school. This character could be jealous of Fem Harry's natural talent and the attention she's getting. So, she makes it her mission to defeat Fem Harry in every competition. She uses her experience and knowledge of the sport to try and outwit Fem Harry, but Fem Harry has her own tricks up her sleeve.
It could be Draco's female counterpart. In this fanfic, she might be just as competitive and haughty as Draco. She would see Fem Harry as a threat to her own status as the top athlete in their school or in their magical sports league. And she would constantly try to undermine Fem Harry's efforts, whether it's by spreading rumors or trying to get her disqualified from competitions.
It could be another female trainer who has a very different approach to Pokemon training. Maybe she focuses more on brute force while Fem Harry is more about strategy. For example, this rival might have a team full of strong but less intelligent Pokemon like Machamp and Golem, while Fem Harry has a more diverse and intelligent team. Their rivalry could be based on their different training philosophies and the desire to prove who is the better trainer.
One possible plot could be that Fem Harry is a talented athlete in a magical sports world, like a female version of Quidditch. She faces discrimination at first because she's a girl in a male - dominated sport. But with her determination and unique skills, she gradually earns the respect of her teammates and rivals. Along the way, she also has to balance her athletic career with her studies at Hogwarts.
Rainbow Dash might also be a main character. She's brave and loves adventure. She could take Fem Harry on some wild rides around Equestria and introduce her to the exciting parts of the world. They might even get into some friendly competitions.
Fem Harry in these fanfics usually has a distinct personality. She might be more nurturing, for instance, taking care of younger students at Hogwarts more often. Her magical abilities may also be presented in a different light. Some fanfics show her having an affinity for certain types of magic that the male Harry didn't, like a special connection to nature - based spells. Her social interactions are different too. She could be more involved in the female - centric groups at Hogwarts, which in turn can influence the overall plot as she brings different perspectives and ideas from those groups into the main story.
There could be the typical high school bully. You know, the one who gives fem Harry a hard time when she first arrives at McKinley High. And then there might be a really nice teacher who takes fem Harry under their wing.
It could be Draco Malfoy. Even if he's not an official champion, he might be jealous of Harry and try to sabotage him at every turn.
Hermione would likely be a strong ally. She's always been Harry's friend and is smart and resourceful. In this scenario, she could help fem Harry with spells and strategies to keep her and her child safe.
There could be a young Salem witch named Lily. She befriends Fem Harry Potter and shows her around Salem. Lily could be very knowledgeable about the local magic and help Fem Harry Potter understand the differences between Hogwarts magic and Salem magic.
There could be an original character who is a descendant of the Uchiha that somehow ends up in the wizarding world. This character could teach fem Harry Potter about the Uchiha ways. Also, Dumbledore could play a role as he always encourages Harry's exploration of different knowledge, and he might be curious about the Uchiha knowledge that Harry is so interested in.
Perhaps an older student who has been overlooked in the past. She's not one of the popular kids but she has a strong sense of justice. When she witnesses something wrong happening to Fawkes, she steps in to protect him. This act of kindness makes her the center of a series of adventures involving Fawkes and the secrets he holds.