One interesting plot idea could be Goku training Caulifla in a new form of Ultra Instinct. This would allow for a deep exploration of their mentor - mentee relationship. Caulifla is already a strong fighter, but with Goku's guidance, she could reach new heights. Another plot could involve them teaming up against a powerful new enemy that neither could defeat alone. They'd have to combine their unique fighting styles and powers to win.
A plot could involve Caulifla being from a parallel universe where she is the only survivor of her race. Goku meets her during a multiverse tournament and decides to help her. As they train and fight side by side, they develop a deep bond that goes beyond friendship and they explore their new relationship while facing various challenges from other universes.
One idea could be Goku Jr facing a new, powerful enemy that has a unique power related to time manipulation. This would force him to train in ways he never has before and seek help from unexpected allies, like some of the older, wiser characters from the original Dragon Ball Z series.
One idea could be Goku and Gohan going on a special training journey to a new planet with unique gravity and energy sources. This would force them to adapt and develop new techniques together.
A plot could involve Bulma creating a new device that Goku needs to use in order to defeat an extremely powerful enemy. Goku has to learn how to operate this device with Bulma's guidance, and they face many obstacles along the way. This would show their cooperation and how their different skillsets complement each other. It could also lead to some comical moments as Goku tries to understand the complex technology. Another interesting plot could be that they are both transported to an alternate dimension where the rules of the Dragon Ball world are slightly different. They have to figure out how to adapt and find a way back home while also uncovering the secrets of this new dimension.
Perhaps a fanfiction where Vegeta and Goku get transported to an alternate universe. In this universe, their roles are reversed, and they have to adapt to the new situation while still trying to find a way back home. They would face challenges that are unique to this new world and learn from each other in different ways.
One interesting plot idea could be that Frieza somehow manages to gain new powers on a distant planet and returns to challenge Goku again. But this time, instead of just brute strength, he uses cunning strategies. Another could be a scenario where Goku and Frieza are forced to team up against an even greater threat from another universe. This would be a great chance to explore their complex relationship.
One idea could be that they have to team up in a new and strange way due to a unique threat. Maybe there's a villain who can only be defeated by a special combination of their powers that they discover through their new 'mate' relationship. For example, they might have to combine their ki in a way they've never done before.
One idea could be that Female Goku and Vegeta have to team up to save the universe from a new and powerful enemy. They start off not getting along well, like in the original series, but as they face challenges together, they develop a mutual respect and friendship.
Maybe a fanfiction where Caulifla develops feelings for Goku during their training sessions. However, Goku, being oblivious as he often is, doesn't notice at first. Caulifla tries to prove herself to Goku by constantly challenging stronger opponents. Their relationship could be a mix of friendship and the start of something more, with a lot of action-packed scenes in between.
At first, Caulifla might be a bit intimidated by Goku's power. But as they train together, she would start to understand his techniques and philosophy of fighting. Goku would also learn from Caulifla's unique approach to battles. Their relationship could evolve into a deep bond where they rely on each other in tough battles. For example, Goku could save Caulifla from a near - death situation, and in return, Caulifla could come up with a creative battle strategy that helps Goku against a difficult opponent.