One idea could be a character going into the chamber not to train for fighting but to study ancient knowledge that can only be accessed within the unique time - space of the chamber.
Perhaps in the fanfiction, Gohan invites some of his friends or family to the hyperbolic time chamber for a special training session. They could all learn from each other and develop new team - based techniques. This would also add an element of camaraderie and character development as they face the challenges of the time - altered environment together.
One idea could be Naruto using the hyperbolic time chamber to train intensively for a new and extremely powerful jutsu. He could emerge with a whole new set of skills that surprise his friends and foes alike.
One idea could be Goku discovers a new power within the Hyperbolic Time Chamber. For example, he might accidentally tap into a form of energy that allows him to manipulate time outside the chamber in a very limited way. This new power could be a key to defeating an upcoming, extremely powerful enemy.
One idea could be Naruto going into the time chamber to train for a new, extremely powerful jutsu that no one has ever seen before. He could emerge with this jutsu and use it to defeat a powerful, new enemy that threatens the Hidden Leaf Village.
A new character created specifically for the fanfiction could be the main character. This character could be an underdog, not as strong as the well - known fighters. But in the hyperbolic time chamber, they discover their hidden potential and strive to prove themselves against the more established heroes.
A powerful demon from another dimension could be the antagonist. This demon, drawn to the energy of the Hyperbolic Time Chamber, tries to take it over. It has the ability to create illusions inside the chamber, making Goku's training even more difficult and dangerous.
It could be a rogue Saiyan from another part of the universe who somehow manages to enter the hyperbolic time chamber. This Saiyan might have a grudge against Gohan's family or be on a quest for power and sees Gohan as an obstacle.
For Naruto, it could accelerate his growth not just in terms of power but also in maturity. Spending a long time alone in the chamber, he might have deep self - reflections and come out with a better understanding of his purpose and responsibilities.
One plot idea could be that Ron and Hermione accidentally discover a hidden passage in the Chamber of Secrets that leads to an ancient wizarding library. In this library, they find a spell book that has the power to reverse dark magic spells, which becomes crucial in fighting the basilisk's venom. Another idea is that they get trapped in a part of the Chamber that has a time - warp effect, and they have to figure out how to get back to their own time while also dealing with the threats within the Chamber. And a third idea could be that Hermione gets cursed by a relic in the Chamber, and Ron has to go on a solo quest to find the antidote while also protecting Hermione from the lurking danger of the Chamber's secrets.
One idea could be Draco secretly trying to solve the mystery of the Chamber of Secrets on his own, not because he wants to help the Muggle - borns but to prove he's better than Harry at finding things out. Another could be a fanfiction where Draco has a change of heart due to an encounter in the Chamber and starts to question his family's beliefs about blood purity.