Son Goku is the strongest man ever known in the history of the universe. He is main character of the Dragon Ball franchise and a recurring guest in RRBZ.
He's first mentioned in Episode 2, but doesn't make an appearance until Episode 7, where he gives the heroes advice and battle knowledge on what to do against the Koopa Clan. He is unable to train the heroes because he was currently busy training Rosemary in Otherworld(she is NOT dead), so that she can be at their level of power.
With her training completed, Goku allowed Rosemary to rescue her cousin from death and had them train for a while before going back to help the heroes. He later sends the Cousin Trio to save the RRBs from their fall to Earth in Episode 36.