A plotline could start with Frieza hearing about Broly's power and being jealous. He then devises a plan to ambush Broly. But Broly, being extremely perceptive in his own way, senses Frieza's approach and is ready for the fight. As the fight progresses, Frieza realizes that Broly is much stronger than he expected and has to use all his dirty tricks to try and win. Or perhaps the plotline could involve Broly being captured by Frieza's forces, and then Broly breaks free and goes on a rampage against Frieza and his minions.
Well, there could be a plotline where the two are forced to team up against a common enemy at first. But due to their mutual distrust and Frieza's underhanded tactics, the alliance quickly breaks down and they turn on each other. Another possibility is that Broly is on a quest for something, like a powerful artifact, and Frieza tries to stop him. This leads to a battle where Broly's brute strength clashes with Frieza's devious plans. There could also be a plotline where Frieza tries to recruit Broly to his side, but Broly refuses and this results in a fight.
One possible plotline could be that Broly, in his rage, accidentally provokes Beerus. Broly, not knowing who Beerus is, attacks him. Beerus, initially amused, decides to teach Broly a lesson but soon realizes that Broly's power is growing at an alarming rate. This leads to an intense battle where Broly pushes Beerus to use his full power. Another plotline could be that Beerus hears about Broly's power and decides to test him. He travels to Broly's location and challenges him. Broly, seeing Beerus as a threat to his friends or his planet, fights back with all his might.
One possible plotline could be that Cell, seeking to prove his superiority, challenges Broly. Broly, in his usual berserk state, accepts without hesitation. The fight could start with Cell trying out his various attacks like the Kamehameha - like Solar Flare and his physical strikes. But Broly's power is just too much and he starts to overpower Cell. However, Cell then reveals a new, hidden ability that he has been developing in secret and the tables are turned for a while.
A plotline could involve Broly being sent to Kale's universe by some sort of interdimensional rift. Kale initially sees him as a threat and attacks. But as the fight progresses, they start to understand each other's power and motives. Or perhaps a fanfic could have a story where both Broly and Kale are training on the same planet. Their training methods clash, leading to a fight where they both learn from each other and grow stronger in the process.
Perhaps there's a plotline where they are on opposite sides of an issue within the village. This causes them to oppose each other physically. It could be something related to a new law or a decision made by the Hokage. As they fight, they also have to deal with the moral implications of their actions. Sakura might be fighting for what she believes is right for the well - being of the villagers, while Neji has his own reasons rooted in his clan's values or his personal code of honor. Their battle would not only be about physical strength but also about the clash of their ideals.
In many fanfics, Broly would likely win. Broly is known for his extreme power and near - uncontrollable rage which gives him a huge strength boost. Frieza, while powerful, has been shown to be outmatched by the likes of Goku and Vegeta. And Broly is often depicted as even more powerful than them in some fan interpretations. So, in a one - on - one fight in a fanfic, Broly has a good chance of coming out on top.
One possible plotline is that Broly mistakes Kale for an enemy at first. But when he realizes she's also a Saiyan, he holds back. They then start to compare their power levels. Another could be that they are both sent on a mission together by some higher - up Saiyan authority. On the mission, they face various challenges and come to respect each other's abilities.
One possible plotline is that Broly is brought to the Harry Potter world as a result of a powerful spell gone wrong. He initially causes chaos with his strength but then gradually learns about the concept of magic and starts to respect it. Another could be that Broly is a hidden protector of Hogwarts, his Saiyan powers being the ultimate defense against a new dark force that the normal magic in the wizarding world can't handle.
A plotline might involve Ross creating a super - weapon to counter the Avengers' powers. The Avengers then have to figure out how to neutralize this weapon and deal with Ross at the same time. Maybe there's a political angle where Ross is trying to pass laws to restrict the Avengers' activities and they oppose him, which escalates into a physical conflict. There could also be a situation where Ross teams up with some of the Avengers' villains to take them on.
A plotline could involve a special Pokemon that both Ash and Paul are interested in. They might compete to catch it, which could involve a series of challenges and battles. Or, perhaps there's a new type of Pokemon training technique that one discovers and the other tries to learn from or outdo. This could create an interesting dynamic in the fanfic.
Another plotline might be that the forces of evil launch a sudden attack on Comet's homeland. Comet has to fight back and in the process, uncovers a conspiracy within the forces of evil that could be used to their advantage. He then uses this knowledge to turn the tables on them.