He seems to be punching you all over the island.
Still, all punches lead to...
You lost your magic seltzer bottle.
You'll have to get a new one.
What was the bottle filled with?
Something made from the voodoo antiroot.
You'll need more root beer.
After LeChuck pulls you out of the grog machine at Stan's, there's a bottle of root beer on the ground.
You could use that to destroy LeChuck.
Pick up the root beer.
Use it on LeChuck to beat the evil pirate and the game.