I've found through further research that I am apparently the only one that did not like the fight scenes in DBS Broly. I found them to be hard to watch, eye straining and uncomfortable to watch. That lame "go Gogeta!" Music didn't help.
Janemba logically makes the most sense as Gaku required fusion to beat him and I doubt Galu was significantly stronger in Wrath of the Dragon, but maybe that's the case.