Once Brolly meets Goku, not even the collar can hold him back. Brolly has had a sparse past with Goku as they were both born at the same time. When Goku was born he was crying like crazy and apparently woke Brolly from his sleep, which enraged him and as a result has kept a grudge against Goku. The battle against Brolly is one of the fiercest battles, the Z warriors have ever experienced. Once Brolly turned Super Saiyan, he was just unstoppable, showing enormous power. So powerful that even Vegeta, the Saiyan prince, believed no one could beat him.
Eventually Brolly took on Goku one on one, and pretty much manhandled him through the whole battle. It took the energy of all the other warriors, including Vegeta, to give Goku enough strength to deliver the final blow to Brolly. After movie 8, Brolly makes two more appearences as he comes back in movie 10, and then comes back in movie 11 as Bio Brolly. Though not a main villan of the series, he has made enough appearences to be considered one and a deadly threat to everyone.
