Another aspect is how the gender - bent characters deal with their powers. If a female - Ben has the Omnitrix, she might use it in a different way compared to the male - Ben. This could be due to her different physical abilities or her different approach to problem - solving. Over time, as she uses the Omnitrix in these new ways, it can lead to significant character development, showing how she evolves as a hero or a person in the Ben 10 - like world of the fanfic.
They explore character development by showing how the same character traits manifest differently in the opposite gender. For instance, if Ben is a girl, her courage might be expressed in a more nuanced way. Maybe she has to deal with different expectations from society within the Ben 10 universe.