Well, one possible plot could be that Goku, as a girl, has to face different challenges in the martial arts world. Maybe the other fighters underestimate her at first, but she quickly proves them wrong with her incredible strength and skills. She might also have to deal with new emotions and how others perceive her femininity in the context of being a powerful fighter.
In a fanfiction where Goku turns into a girl, the plot could involve her exploring new relationships. For example, her interactions with Vegeta could change completely. Vegeta might be initially confused by this transformation but then start to respect her in a different way. Also, she could form new friendships with female characters who help her understand this new form better and they could team up to face common enemies.
In the fanfic, perhaps Goku's transformation into a girl is the result of a magical spell. As a girl, she might start to see the world from a different perspective. She could be more in touch with her emotions and this could either enhance or hinder her fighting abilities. For instance, she might be more empathetic towards her enemies, which could lead to some interesting moral dilemmas during fights. Her training regime might also change as she adapts to her new body.
Well, perhaps the story could revolve around Kirito's relationships. As a girl, his/her interactions with Asuna could change significantly. They might develop a different kind of friendship or even a romantic relationship that has new dynamics compared to when Kirito was male. Also, other characters like Klein might react in very interesting ways to this transformation.
One possible plot could be that Merlin, after being hit by a strange spell, turns into a girl. His friends in Camelot are initially shocked. Arthur might be both confused and a bit protective in a new way. Merlin has to deal with the new physical form while still trying to protect Arthur and Camelot. She would have to adapt to the different expectations placed on women in Camelot, like different dress codes and social behaviors, all while hiding her true identity as the powerful sorcerer Merlin.
One possible plot could be that Sonic, after being exposed to a strange Chaos Emerald malfunction, turns into a girl. As a girl, Sonic might face new challenges in terms of her identity. For example, her friends like Tails and Knuckles might initially be confused. Sonic could then have to deal with different reactions from her enemies too. Maybe Dr. Eggman would underestimate her in this new form, but she would prove him wrong by using her speed and skills in new and unexpected ways. She might also discover new aspects of her own personality that were hidden before the transformation.
One possible plot could be that Natsu, after being hit by a strange magic spell during a battle, turns into a girl. His friends are initially shocked but quickly adapt. Natsu, as a girl, discovers new aspects of his own personality. For example, he might find that he is more in touch with his emotions. He could also face some challenges like having to deal with different clothing styles and the way others now perceive him. As the story progresses, he tries to find a way to break the spell while still learning important lessons about himself and his relationships with others.
The plot could involve a mad scientist who was experimenting with a new type of candy - to - human transformation. The gumball was an accidental subject. Once it turns into a girl, she discovers that she has some unique abilities related to her gumball origin. For example, she can bounce really high or is super sweet - smelling. She then uses these abilities to help her new friends in the town she finds herself in, and at the same time, tries to reverse the transformation if she wants to.
One possible plot could be that Firestar, as a girl, has to face different challenges in the clan. Maybe she is initially not accepted by some cats who are used to the male Firestar. But she proves herself by her hunting and fighting skills. She might also have a different perspective on relationships within the clan, like forming new friendships with female cats and having a different dynamic with male cats.
One possible plot could be that Goku Black starts to have doubts about his evil actions after experiencing some self - reflection. Maybe he witnesses an act of great kindness that makes him question his motives.
Well, perhaps in this fanfiction, Aang turns into a girl due to some strange magic or spirit encounter. And then she finds that she can connect with certain female spirits in a new way. This leads her on a journey to understand this new aspect of herself and also use this new connection to bring balance to the world in ways she hadn't considered before.
One possible plot could be that Luffy, now as a girl, has to navigate the pirate world in a different way. Maybe the crew has to deal with different reactions from other pirates and people they encounter. Some might underestimate her because she's a girl, but Luffy's strong will remains the same, and she shows everyone that gender doesn't matter when it comes to being a great pirate.