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.
In such a fanfiction, perhaps future Gohan could warn present - day Gohan about upcoming threats that he has faced in his own timeline. He might share his experiences and knowledge, which could make present Gohan a stronger fighter and a wiser person.
Piccolo might also be a savior. He has a soft spot for Gohan since they trained together. He could use his strategic mind and powerful attacks to outwit Raditz and rescue Gohan. Maybe he teams up with Goku for an even more epic rescue mission.
Perhaps Gohan's own overconfidence could lead to his death. He might underestimate an enemy's power or a dangerous situation and make a wrong move that results in his end. For example, he could rush into a fight without proper preparation thinking he can handle it easily.
A possible plot twist could be that future Gohan is actually an impostor sent by an enemy to manipulate the real Gohan. Another twist might be that when they meet, their powers combine in an unexpected way that causes some sort of time rift or a change in the timeline.
Naruto would probably be the most interested. He loves making new friends and Gohan's power would surely catch his attention. He'd be eager to learn about Gohan's world and his abilities.
It could be a new, unknown enemy. Maybe someone from a far - off planet who has a grudge against the Saiyans. This character could be really powerful and sees Gohan as an easy target at first, so he throws a punch.
He could face Jiren again. But this time, Gohan would be the one to come out on top. Maybe he'd have studied Jiren's fighting style thoroughly and found a way to counter it.