In Jaws for nintendo all you have to do is first deplete all of Jaws' power, its easier the higher in power you get by going port to port with the shells you find brawling w/ jellyfish and stingrays. Once you get to the scene with Jaws and the boat wait till Jaws is directly in front of the boat but not too close and hit your strobeby pushing A. Once he pops up wait a second for him to spin and show his belly the stab him with the boat. He dies and then thats it no really good ending, I know cause I just beat it right now, by the way the other comments were no help!