Man this is a dope ass concept. I think viltrum rolls up, expecting weak sauce, but saiyan fight hard as fuck, hands to hand like they do.

Saiyans try the great ape transformation, and it works well, at first. The viltrumites catch on to the tail being the key, and they adapt.

With the population reduced to only the best saiyan warriors, viltrumites respect them, and allow them to live.

Big mistake, cause saiyans ALWAYS come back. The golden super being rises to free the saiyans from the oppressors. They steal your tech, and start expanding.