First off, be sure to jump very time Klubba or Kudgel hit the ground, you jump so you don't get stunned by the shaking. This is key to you winning this fight
with the heavyweight Kremlings. Dodge them falling from the top of the screen three times, and pick up the TNT Barrel that falls down from the sky. Next, let one of them land on the ground, and wallop one of them with the TNT Barrel (they make this really satisfying ROAR
that echoes through the whole swamp). They will go through this same set-up
for two or three more times, and then they switch tactics. They will return to the
screen to attempt to jump on you (don't worry, they won't leave screen). They will
attempt three jumps, a TNT Barrel will fall, and they will leap off the
screen. Then all you need to do is dodge thier fall, and throw the TNT Barrel
at them. Do this two or so more times to send them into the swamp.