To beat the Green Jugger Nut on stage 15, do the same thing that you did with the white one on stage 5, which is to bait him into attacking, then dash to avoid the attack, then run up and hit him. Repeat over and over again to do him in. You have more room to dash around him, so it’s easier to find a place to run to, but make sure to time your dashes right when he jumps way high into the air to try to crush you. Repeat until he’s dead.
The Orange Jugger Nut seems nearly impossible at first, but there is a technique to beating him. First, take out all of the Jelly Donuts using the gummy whip. There are four of them in all. Then, when the Jugger Nut makes the Boston Creams, entice them into blowing themselves up but avoid the blast. Blow them up close enough to the Jugger Nut to damage it, too. Use your gummy whip to attack the Jugger Nut from afar.
Whenever you see a crowd of enemies across the wall from you or on the other side of the door, if they are within striking distance with the sword, then take them all out. They can’t damage you and they will not try to attack you, but you can attack them all you want. If you can’t reach them with your sword, use any one of your ranged weapons to take them out.
You can beat any stage you want without even bothering to collect any stars. All that you have to do is go to the end of the stage and talk to the Teleporting Fat Guy. Go back later and get the stars, especially after a weapon or clothing upgrade or two.
In fact, on many stages you won’t be able to get any stars at all, because you won’t have the right weapons necessary to get where you need to go. Go back to these stages later on, after you beat the next boss (or even the next two bosses) and collect the stars that you couldn’t get to before.
Talk to the squirrel every time you beat a stage, because he says something different every time depending on your current stage. What he has to say is not necessarily relevant or even useful, it’s just funny.