Summoned beasts usually appear in fantasy or science fiction novels. Summoned beasts are creatures with special abilities. They can usually summon various weapons or equipment to help their masters fight.
Some of the famous novels that turned into summoned beasts included the Harry Potter series, the Lord of the Rings series, and Journey to the West. In these novels, summoned beasts usually had their own personalities and stories. Some summoned beasts even developed emotional relationships with their masters.
In novels that transformed into summoned beasts, there were often all kinds of magical creatures and magic, as well as all kinds of adventures and battles. These novels usually attract the interest of many readers because they often have thrilling plots and imaginative worlds.
Perhaps there's a powerful artifact that Gohan touches, and it transforms him into a girl as a form of curse. In this new form, Gohan starts to notice different things about himself and the world around him. He might have to learn new ways to fight and move, as his body is now different. His relationships with his friends like Videl and Piccolo could also change, as they try to help him adapt and find a way to break the curse.
It could be a new villain who is specifically targeting Gohan because of his new form. This villain might see Gohan's transformation as a sign of weakness or an opportunity to mess with the Z - fighters. Maybe they want to use Gohan's confusion and the chaos it causes among his friends and family to their advantage.
In this fanfiction, Beast Boy could turn into a girl because of an encounter with an alien artifact. As a girl, he discovers new aspects of his powers. Maybe he can now communicate with different animals in a more empathetic way. His relationships with the other Titans change too. Starfire might take her on shopping sprees, thinking she needs more 'girly' things.
One common theme is adventure. Since Gohan has his Beast form, they might go on adventures together fighting enemies. Another theme could be romance, exploring their relationship deeper.