I found out how to get the button on on the bottom of the high area: First get the bubble launcher from bubble buddy and then use it to push that button. Now I need help with the Plankton bossfight. At the end it seems to be endless, that is, you just go around and around with Plankton with no definite end. How do you finish? Any help would be much appreciated.

I forgot how, I don't play the game that much, and you can just look on google for that.