If Broly participated in the Tournament of Power, he would be an absolute powerhouse. His raw strength and uncontrollable rage could either make him a wild card that disrupts the whole tournament or a key player for his team. He might start by randomly attacking opponents without much strategy, but as the fight goes on, his natural fighting instincts could kick in and he could become a real threat to the strongest fighters in the multiverse.
Bulma could be another character paired with the reborn Broly. She might be the one to help him understand the modern world if he is reborn in a different time period. She could use her intelligence to create devices that help Broly control his power better or she could just be there to provide some comic relief in the midst of all the intense Saiyan drama.
He could team up with Luffy. Luffy is always open to new allies, and Broly's power would be a great addition to the Straw Hat crew. They could go on adventures together and face powerful enemies.
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.
Another strong opponent could be Hit. Hit has the ability to manipulate time with his time - skip technique. This would give him an edge against Broly. Broly's brute strength might not be enough when Hit can literally disappear and reappear at will, striking at Broly's weak points during his time - skips.