Personally, I find this to be a stupid question. True, Goku was only able to beat him with the support of everyone that was there, but Goku has gotten way stronger since then. I'm sure that SSJ3 alone would take Broly out with little difficulty. But you showed Goku in his SSJG form. Goku's power multiplies with each transformation. I bet that if they went against each other in the form that you showed, it would be like when Goku fought beerus-sama.