A plot could involve a love triangle where Female Frieza has feelings for Goku, but Goku is oblivious and focused on his own goals. Meanwhile, another character is also interested in Goku. This could lead to a lot of comical and tense situations. Or perhaps Female Frieza challenges Goku to a series of contests not related to fighting, like cooking or dancing, to prove she can be better than him in other areas.
In a fanfiction, there could be a story where Goku and Female Frieza are stranded on an uninhabited planet. They have to rely on each other to survive. At first, they are at odds, but as time passes, they develop a mutual understanding. Female Frieza might start to use her intelligence in ways Goku never expected, like building shelters or finding food sources, and Goku would use his physical abilities to protect them from any threats on the planet.
One idea could be that Frieza and Goku are forced to team up against a new, even more powerful enemy. They start off hating each other but gradually learn to respect each other's skills.
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 after the fusion, they have to deal with a new, even more powerful enemy that is threatening the entire universe. Their combined powers give them unique abilities that they have to learn to control quickly.
In some versions, the female Goku could be part of a prophecy. The two Gokus meet, and at first, there is some confusion and misunderstanding. But as they get to know each other, they discover that they are key to fulfilling the prophecy. They combine their powers and defeat an ancient evil that was threatening both of their worlds.
One interesting plot could be Goku and Fem Frieza having to team up against a new, powerful enemy. Maybe this enemy is threatening both of their planets or has some power that neither can defeat alone. Another plot could be Fem Frieza falling in love with Goku and trying to change her evil ways to be with him, but struggling with her past and her reputation among the villains.
One idea could be that Frieza, in a strange turn of events, spares Yamcha during a battle and then gradually becomes intrigued by his tenacity. This leads to them forming an unlikely alliance against a common enemy. As they spend more time together, they start to understand each other's motives and personalities, and a unique bond forms between them.
One idea could be that Frieza, after being resurrected yet again, finds himself in a situation where he has to team up with Gohan. During their time together, they start to understand each other's motives and past traumas. Gohan's kindness and sense of justice gradually influence Frieza in unexpected ways.
One idea could be that Goku and Goku Black are forced to team up against an even greater threat from another universe. They start to understand each other's fighting styles during the battle and gradually develop a grudging respect for one another.
One idea could be a story where Bulma creates a new device that accidentally sends Goku and her to a parallel universe. There, they have to work together to find a way back home while facing new and strange enemies. Another could be a time - travel plot where they go back in time to before Goku met Chi - Chi and Bulma realizes she has feelings for him. The third idea is a story where Goku and Bulma get trapped on a deserted planet and must rely on each other's skills to survive and escape.
One idea could be a crossover universe where Goku somehow ends up in the Naruto world and meets Sakura. They could team up to fight a new common enemy that is causing chaos in both their worlds. Maybe this enemy has the ability to steal energy like the Saiyans but also uses genjutsu like the ninjas.