
Ghirahim is the Demon Lord who rules the surface world. He's incredibly cocky and will fight you barehanded at first. His right hand will trace your sword's movements and he'll catch your blade between his fingers if you telegraph the directions of your attacks, so try to confuse him with quick strikes and by tracing circles in the air with your sword. If he manages to grab hold of your sword, try to pull it away before he yanks it from your grasp and wields it against you. You can use a Shield Attack to knock it back out of his hands or wait for him to throw it at you (dodge it, of course!).
Scaldera is a molten fiend covered in a rocky shell. Its eye is its primary weak point, but to strike at it you'll need to dismantle its outer carapace. Bombs should do the trick, but they'll only really work if detonated within. The monster will crawl along the narrow arena, attempting to step on you with its magma feet, as well as shoot giant fireballs at you from either end of the stage. Dodge these attacks and, when it opens its mouth to inhale hot air, toss a Bomb in along with it. The blast will break off pieces of the rocky coating.
Moldarach is a giant scorpion, a fully-matured Aracha that has dwelt in this facility for a thousand years. Its weak points are the "eyes" inside of its claws, which you can strike with your sword but only if you slice them down the middle, without hitting the armored pincers themselves. At first it will try to grab you with its claws - if it gets you, shake the Wii Remote and Nunchuk violently to break free - but if you deal enough damage you'll break its claws right off. Fortunately, you can tell when it's about to attack because the "eye" on one of its claws will glow a reddish hue.
Koloktos is held together by red "cores," energized by Ghirahim so it can smash you to pieces. Dodge its many-armed attacks and watch for one of the cores to reveal itself. Your Whip can tug on the hooks protruding from the cores, yanking them free and dismantling the arms entirely. The catch: the cores only reveal themselves as the arms unleash their mighty attacks. You'll have to tread carefully without keeping too much distance.
Tentalus is trying to tear the Sandship apart with its gargantuan tentacles. You'll have to cut into a few of them at first before the monster will truly reveal itself, but only a Skyward Strike will do the trick. Point your sword upward to charge power, but make sure you don't get knocked around in the meantime. After you've dealt enough damage to the tentacles, Tentalus will rise up from the waves and attack you directly. Its giant eye is its weak point, and because it's out of your sword's reach only the Bow can hit it.
Bilocyte is the parasitic tentacle that has latched onto the sky god Levias and taken control of him. It fires noxious goo from its eye stalk, but you can repel the attack with your sword to launch it right back at the beast. In order to get in an attack against its central eye, however, you'll first need to deal with its defensive mechanisms - the fins on either side. By swinging your sword to the left or right, you can send back its goo attacks at different angles in order to direct them at the fins. Once the fins are out of the picture, use vertical sword strikes to send the balls of gunk straight back to the eye.