Well, in some Gohan time travel fanfictions, he might travel back to the Saiyan saga. There, he could try to convince the other Saiyans not to come to Earth, or he could help the Z - fighters prepare better for their battle. He might also use his time - traveling to find out secrets about the Saiyan race that were lost over time, like hidden powers or techniques that could be used to defeat future enemies.
One interesting plotline could be Gohan traveling back in time to prevent certain tragedies. For example, he might go back to stop the death of his father, Goku. This would change the entire course of the Dragon Ball Z story. Another could be Gohan using his knowledge from the future to train his younger self more effectively, leading to a much stronger Gohan at an earlier stage.
In a Gohan time travel DBZ fanfiction, there could be a plot where Gohan travels back to the Cell Games. He could use his future knowledge to help Goku defeat Cell more easily. Maybe he'd share some new strategies or power - up techniques. Also, he might try to change the outcome of the fight in a way that doesn't lead to Goku's sacrifice. This would not only change the relationship between Gohan and Goku but also the overall power balance in the Dragon Ball Z universe.
Chapter 153, "Word Spreads, Director Sun Takes the Lead in Shipping the CP!", is the clearest early answer because it turns Director Sun Takes's situation into a concrete plot event.
Chapter 129, "Spent Millions Only to Drive Traffic to Jiang Li?!", is the clearest early answer because it turns Huo Ziyang's situation into a concrete plot event. Early on, When they saw that the live chat was full of praise for Jiang Li,....
Chapter 137, "Lai Fu's Death Has Another Cause", is the clearest early answer because the violence around Cause Jiang Li becomes final instead of hypothetical. A useful checkpoint is the way the scene starts with Jiang Li personally went to Lai Fu's tomb and performed a small...
Chapter 143, "How about Grandma introducing a girlfriend to you?", is the clearest early answer because it turns Princess Wen's situation into a concrete plot event. Early on, Is there really such delicious fish soup in the world?.
Chapter 342, "This is our Hua Country's archery", is the clearest early answer because it turns Daniel's situation into a concrete plot event. Early on, Some horses fell in the mud pits and never got up, some remained....
Chapter 27, "Signing Jiang Yan is fine, but you have to follow along too.", is the clearest early answer because it turns Shen Lan's situation into a concrete plot event.
Chapter 278, "Who Are These People Who Idolize Jiang Li?!", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. The chapter turns that into something concrete by moving from People from the fan club also got word that Jiang Li was soon to...
Chapter 29, "The 36 Strategies - Sneak through Chen Cang", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event.
Chapter 61, "Young Master Before vs After Going to the Countryside", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Hahahaha, oh my god, Jiang Li's mouth is even more venomous.
Chapter 205, "The Fairy Descends to the Mortal World", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.