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.
A possible plot idea is a time - travel fanfiction. What if Frieza went back in time and tried to prevent Goku from ever becoming a Super Saiyan? He could change key events in Goku's past, like interfering with his training under Kami or Master Roshi. Then Goku would have to find a way to regain his power and face Frieza in this altered timeline.
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 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.
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.
One idea could be that Female Vegeta and Goku are forced to team up for a special mission. They start off bickering as they usually do, but as they face challenges together, they begin to respect each other's fighting styles more. Maybe they have to battle a new, extremely powerful enemy that neither could defeat alone. This situation could lead to some interesting character development and a budding friendship or something more.
One interesting 'Dragon Ball Z TG Frieza' fanfiction could be one where Frieza has a character transformation that makes him question his evil ways. For example, he might be exposed to the kindness of the Earthlings and start to have a change of heart.
An interesting plot could be that the OC is the last of the Frieza race after a great catastrophe. They are on a mission to rebuild their race but in a more benevolent way. However, other races are suspicious of their intentions, and they have to prove themselves worthy of trust.
One interesting storyline could be a female Frieza race character trying to redeem her race's bad reputation. She could go on a journey to help planets in need, much like Goku and his friends do. Another could be her getting involved in a power struggle within the Frieza race, where she has to use her wits and new - found powers to survive.
Another interesting plot could be that the gamer aspect brings in virtual reality elements. The Z - fighters enter a virtual world where they have to fight enemies with different rules. This virtual world could have power - ups and obstacles that are based on video game concepts, like finding hidden keys to unlock new areas or defeating bosses to gain special abilities that they can then use in the real Dragon Ball Z world.
One idea could be a crossover with the Naruto universe. Goku and Naruto could team up to fight a common enemy. Maybe they face an evil villain who has the power - stealing abilities like Cell and the ability to use powerful ninja jutsus. Another plot could be a crossover with One Piece, where Luffy and Goku have a friendly competition about who can eat more food and then end up having to work together to defeat a new threat at sea that has the strength of Saiyans and the deviousness of pirates.