Oozaru
Oozaru (pron, Oo-Zar-loo) or Great Ape, is the state Goku transforms into when viewing the full moon. In this form Goku's power is increase a tenfold and his size is much like King Kong. He has no control in this form and goes totally berserk destroying buildings, trees, friends and foes alike.
For this puzzle cache, Goku has transformed into the great ape and his going on a rampage. However, the Oozaru has one weak point. To solve the puzzle you must discover what is this weak point and exploit it to stop the Oozaru. Once you do that you can get a puzzle piece to find the dragon ball.
By the way, one of the rocks in the UPR that hides the cache is fossilized. It's really cool.
Yamcha and his faithful friend know of this weakness and have used it before to stop the Oozaru. You should check their cache pages carefully!