I got a book named "Hawaiian Legends of Ghosts and Gods" :^)
It's online as well, luckily
http://www.sacred-texts.com/pac/hlog/I recall this story about a cannibal Shark-Man:
http://www.sacred-texts.com/pac/hlog/hlog13.htmI don't think a sharkman that has a mouth filled with teeth on his back has been done before :^)
This is my favorite story from that book:
http://www.sacred-texts.com/pac/hlog/hlog12.htmBut I'm not sure if this story would fit what you're going for
I also have plenty of other books on Polynesian mythology, but I can't really recall reading anything that would fit in a scooby-doo-esque story. I'll try to plow through the annotations I made in em to see if I can find anything useful.
Adolos are pretty interesting too, but they are shadow creatures in Kwaio mythology. And Kwaio are Melanesian and not Polynesian, so they might not fit the tiki theme.
Hope that helps (^: