When you get to the mountain where the Jellyfish is taking a shower, after a short intermission sequence, he will hover toward you. Try to avoid him. He will sit on the ground for a few seconds. While he is sitting, he will make a shockwave, similar to what Robo Sandy did in the Posidome. If you avoid the shockwave, the King Jellyfish will sit down for five more seconds. While he is still sitting, whack him (Square). He will jump up and make five to six little pink jellyfish. You will now have to avoid the small jellyfishes and the big jellyfish. This time, the big jellyfish will create two shockwaves. When he sits down (if you did not get hit by the shockwaves) hit him again. The third time, he will make five to six little blue jellyfish (faster then the pink ones). Avoid the two shockwaves and the pink and blue jellyfish. Once you hit the big jellyfish for the last time he will give you a jar of jellyfish jelly. He opens the curtains behind him, where there is a slide down to a place that leads to Jellyfish Rock. However, first go in the pool where you fought the big jellyfish and get the shiny objects.