Ultimate: Food Becomes Strong was a novel by Moth in the Moonlight. The story was about the protagonist transmigrating to the Ultimate Class One and obtaining the ability to go to the food world. In the world of food, the protagonist could obtain the corresponding combat index and special ability after eating various delicacies. The novel focused on the delicacies and the lives of the diners. The early story was exciting and moving, but the later story was slightly more conventional. Even so, this novel is still worth recommending.
Well, it could be about Gohan and Naruto teaming up to fight a common powerful enemy. Maybe an evil force from another dimension is threatening both their worlds, and they have to combine their unique powers and skills to save the day.
It could be a powerful demon that has the ability to absorb the powers of others. This demon has been observing both Gohan and Naruto from the shadows and wants to take their powers to become invincible.
In a crossover with the DC Universe, Darkseid would be a great antagonist. His immense power and his desire for universal domination would put him at odds with Ultimate Gohan who stands for justice and protecting the innocent.
Obviously, Gohan as a girl would be the main character. His family members like Goku, Chi - Chi, and Goten would likely be in the story. They would have different reactions and interactions with Gohan in his new form.
Well, it could be about Gohan's daily life experiences as a girl. Maybe he has to deal with different social situations, like how his friends and family react to his new form.
Perhaps Ultimate Gohan could cross over into the world of Star Wars. He could use his powers to assist the Jedi in their fight against the Sith. His ki blasts could be like a new form of Force power in that universe.
There were a few novels that could be recommended, including Those Years Living in the Future World of Dragon Ball, If Dragon Ball, Latiz took Gohan away, and The Strongest Sun Gohan of Dragon Ball. These novels all used Gohan as the protagonist, telling his growth and adventures in the Dragon Ball world. These novels might satisfy your need for Gohan to be the protagonist.
In this fanfiction, Gohan might learn valuable life lessons from Grandpa Gohan. Maybe Grandpa Gohan would teach Gohan some old - fashioned martial arts techniques that have been forgotten over time.