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.
One popular Broly and Kale fanfic is 'The Saiyan Bond' which explores their relationship in a unique way. It shows how they might train together and overcome challenges side by side.
One possible plot could be that they meet during a universal tournament. They start off as opponents but soon realize they have more in common than they thought. They end up joining forces to take on stronger foes.
Sure, there are quite a few. In many of these fanfictions, the authors play with the power levels and personalities of Kale and Broly. They might have Kale being initially intimidated by Broly's raw power, or Broly being curious about Kale's unique transformation. Some stories might even delve into their backstories and how those could influence their interaction when they meet. It's always exciting to explore these different interpretations in fanfiction.
One common theme is power. Since both Broly and Kale have incredible power, many fanfics explore how they control it, train to improve it, or use it to protect their race.
It's hard to say for sure. In the official lore, Broly is extremely powerful with his Legendary Super Saiyan form. But Kale also has her Berserker form which gives her a great boost in power. In a fanfic, it could really go either way depending on how the writer wants to portray their powers and the circumstances of the fight.
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.