If you saw the Dragon Ball Super Broly movie, we never got to see Gokuu fight Broly using his Ultra Instinct form (just saw him go up to Super Saiyan Blue Kaio-Ken). Instead, we were treated to the latest Gogeta fusion where he makes easy work of Broly in Super Saiyan Blue form. Their fight was so intense to the point that it transcended space and time (and before that, probably rushed climate change by over 9,000 months). However, it isn’t Gogeta that can do that as he fought Broly. Remember when Gokuu first showed up in Ultra Instinct form after fighting Jiren? We thought that his very being perished to the point that no single trace of matter of him was left. However, he transcended space and time to come back as Ultra Instinct Gokuu. If Ultra Instinct Gokuu is powerful enough to re-materialize from using so much energy fighting Jiren, then that’s a good indication to determine that he can at least go toe-to-toe against Legendary Super Saiyan Broly to the point that they can transcend space and time.

As Ultra Instinct Gokuu, he succeeded where Broly failed, he actually defeated a fusion of two Saiyans, Kale and Caulifa as Kefla. However, we can admit this comparison isn’t 100% fair since Broly had to fight a fusion that achieved Super Saiyan Blue. On the other hand, we must also keep in mind that Kale is also capable of achieving the Super Saiyan form that makes her resemble Broly (including muscles, facial structure, and hair style), so the fact that one half of that fusion is based on a female Broly is a basic and reasonable indicator as to how Gokuu could handle the Broly of his universe.

Of course when Gokuu fought Kefla, they were fighting in a tournament within the parameters of the rules. They also couldn’t fly and weren’t essentially allowed to kill each other. If they fought without rules, we can assume that the flow of the fight could have gone differently. In the end however, UItra Instinct Gokuu could still hop on Kefla’s fireballs, fire a Kamehameha powerful enough to eliminate her from the arena, and destroy their earrings in the process. Considering Ultra Instinct Gokuu showed this much power in a setting where there are rules, just imagine what he can do in a fight with no rules and with the freedom to fly.

As highlighted in the movie, Broly may have the genetics, natural instincts, and training to be the perfect fighter, but he lacks the experience of Gokuu. Even in his Rage mode, he was still exhibiting some difficulties fighting Gokuu and Vegeta due to his lack of experience in a fight. However, he can easily overpower Super Saiyan Blue Gokuu and Vegeta when they’re not fused when he achieves Super Saiyan. When Gokuu can achieve Ultra Instinct, not only does he have unimaginable power on his side, but a wealth of experience. When you combine those abilities and his experience together, Ultra Instinct Gokuu is the ultimate fighting machine. Is he strong enough to go against Whis? We don’t know, but considering how Whis easily toyed with Broly when Gokuu and Vegeta were trying to work out how to do the fusion dance, Ultra Instinct Gokuu, who even earned the praised of Whis and Beerus is likely to make easy work of Broly in the same manner as Super Saiyan Blue Gogeta.