Interesting fact about the plasm wraith: when throwing rock pikmin at some fire plasm, one or two pikmin may shoot up into the air, REALLY high. I've had it happen twice while trying to complete the Oak in one day: first with one pikmin and then on another try two at once. If you aren't whistling at the ground they are landing on right when they land, they die. I saved one of the 2 the 2nd time.