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, 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.
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.
The character development could be interesting. Goku, now a girl, would have to adapt to different social expectations. She might become more empathetic as she experiences some of the things that female characters in the Dragon Ball universe face. For example, she could be more in tune with the emotional needs of her friends and family.
Obviously, Goku Black himself is the key character as the story revolves around his transformation. Goku would also be important as he could be the one who shows Goku Black the path of good, either directly or indirectly.
Krillin would probably be one of the first to be accepting. He's always been Goku's friend and would likely see Goku's inner strength regardless of the physical form. He might even joke about it a bit at first. Vegeta, on the other hand, would be initially shocked and perhaps a bit dismissive. But as he sees Goku's power in the new form, he would gradually come to respect it. Gohan would be very curious and would want to know how this transformation happened and what it means for their future battles.
His relationship with Chi - Chi would be very different. Instead of being her husband, he's now like a son to her. She would be super protective. And with Gohan, it would be more like they are brothers. Gohan would have to look out for his 'baby father'.
The Real Monkey King was a Chinese martial arts novel that told the story of Sun Wukong and the Bull Demon King. The main plot of the story was as follows:
Sun Wukong was the Monkey King of the Flower-Fruit Mountain. He had become a member of the Immortal World because he had eaten the immortal peaches of the Taishang Laojun. Later, he was given the title of "Great Sage Equal to Heaven" by the Jade Emperor and was forced to live under the Five Fingers Mountain for 500 years. During this time, he got to know Princess Iron Fan, Bull Demon King, and others.
Five hundred years later, Sun Wukong was recruited by Tang Sanzang and decided to go to the Western Paradise to obtain Buddhist scriptures. Along the way, he had a series of fights and adventures with Bull Demon King, Princess Iron Fan, and the others. The real Monkey King incident was a conflict between Sun Wukong and Princess Iron Fan.
The fake Sun Wukong was disguised by Zhu Bajie and Sand Monk, the disciples of Tang Sanzang. They wanted to use the conflict between Sun Wukong to stop Sun Wukong from learning the scriptures. However, Sun Wukong had already seen through their plot and decided to fight them. In the battle, Sun Wukong and Princess Iron Fan joined forces to defeat the fake Sun Wukong, but there was a more complicated conspiracy behind the fake Sun Wukong.
In the end, Sun Wukong successfully defeated the conspiracy of Princess Iron Fan, Zhu Bajie and Monk Sand through his wisdom and courage and successfully arrived at the Western Paradise to learn the scriptures. In this process, he gradually understood the true meaning of life and the way of life.
Well, Vegeta would be a likely character. He might be initially suspicious of the female Goku. Maybe he thinks she's a threat or just can't believe there's another Goku - like being. He could be there to add some comical moments as he tries to understand the situation.