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.
Goku could be a likely ally. Despite their initial conflicts, Goku has a way of seeing the good in people. He might approach Broly and convince him that they can work together to win the Tournament of Power for their universe. Their combined strength would be a formidable force.
In a crossover with One Piece, Luffy could be an ally. Luffy is known for his open - mindedness and ability to befriend almost anyone. He would see Broly's power and might try to get him to join his crew or at least fight alongside him against common enemies. They could have some really fun interactions, like Luffy trying to make Broly laugh or share his love for food with him.
In a crossover with the Naruto universe, Naruto himself could be an ally. Naruto has a way of seeing the good in people, and he might try to reach out to Broly and convince him to use his power for good. His ability to befriend and understand others could be key.
A 'Goku and Videl' fanfic can explore various aspects of their relationship. It might show their friendship evolving into something more. For example, it could depict how they support each other during tough times. Maybe Videl discovers new sides of Goku as they train together, and this deepens their bond.
Since Broly has a rather wild and untamed personality, Naruto could learn to be more in touch with his primal instincts. This doesn't mean Naruto would become a brute, but rather he could find a new balance between his kind - hearted nature and a more aggressive side when necessary. For example, in negotiations or battles, Naruto could be more intimidating. Also, Broly's loyalty to his own beliefs (even if they are sometimes extreme) could inspire Naruto to be more firm in his own ninja way.