Her character development would likely be different as a girl because she would face different challenges. For example, she might have to deal with the objectification that female ninjas sometimes face. This could make her more aware of gender inequality and she could become an advocate for female rights in the ninja world.
If Sasuke becomes a girl, her appearance would transform in multiple ways. Physically, she'd probably have a smaller frame and less muscular build. Her hair could grow out to be really long and silky, which she might tie up with ribbons or hairpins. Her eyes could be made to look bigger and more alluring. Her skin might be smoother and have a bit of a glow. And she would start wearing more feminine accessories like earrings or a necklace. Her ninja outfits would also be redesigned to be more like a kunoichi's, with a shorter skirt perhaps and a more decorative top, while still maintaining some elements of her original style for the sake of recognition.
Perhaps she is a time - traveler from the future. She has knowledge of future events that will endanger the ninja world and Sasuke. So, she tries to enlist his help, and in the process, a relationship develops between them. She might have unique abilities due to her time - traveling origin.
Another possibility is that Natsu is turned into a girl by a magic spell gone wrong. As a girl, he discovers new magical abilities or a different way of using his existing fire magic. Maybe the transformation also affects his personality slightly, making him more empathetic and in tune with the feelings of others around him.
Sasuke could also have a complex mix of emotions. On one hand, he has a long - standing relationship with 'Naruto' as a male friend. Now that he knows Naruto is a girl, he might start to feel a different kind of connection. He may become more protective, but also a bit confused about his own feelings towards this new - found knowledge. He might even feel a bit betrayed that Naruto has hidden this fact for so long.
He could also face challenges within his own guild. Some of the members might tease him, while others might be overly protective. Natsu as a girl would have to navigate through these new social dynamics. Also, his appearance as a girl might attract unwanted attention from some villains who see him as an easier target, but he would prove them wrong with his strength.
Well, in such a fanfiction, Beerus as a girl might have a different approach to her relationships. Maybe she would be more empathetic towards the other characters. For example, she could form closer friendships with Goku and Vegeta. Instead of just being feared, she might be more approachable and could even start training with them in a more collaborative way.
Well, maybe Ben 10 gets transformed into a girl by some alien device malfunction. Then he has to deal with all the new experiences like how people treat him differently, and he might discover new powers related to his new form.
Well, it could be about Steven having some sort of magical or scientific accident that turns him into a girl. Then he has to deal with the new body, different social expectations, and how his friends and family react to this big change.