How do you beat the swamp on subspace emissary?

You must beat Tabuu, the last boss of the whole game. It is not necessary that you have to be at 100% to reach him!. I reached him at 70%. Ok now listen , i mean read..

After you beat him, go back to the swamp area , and thre will be a new door! In there will be jigglypuf. you unlock him. or defeat him, then swamp will be complete!!!