Here's what we missed:
First Shaggy would have ran away.
Fred would have built some elaborate trap that wouldn't have worked but may beat the hell out Goku.
Goku would have been easily fooled by Shaggy in disguise & given a bag of sensu beans.
Over eating the beans gives supper powers to Shaggy to beat up Goku
During the fight Goku dropped the Dragon Balls.
Shaggy found the balls & wished he had a sandwitch instead, causing the balls to turn in to sandwiches.
Goku is try to save the balls as each one that Shaggy consumes only makes Shaggy more powerful & psychotic.
This way to short.