Four Swords: Bosses

The Guardian of the Sea Trees
Dodge the plants until the flowers are revealed. When the flower is the color of your tunic, attack that flower. Sometimes it may even show 2, just keep doing the process. When the handles appear, quickly grab onto them and pull, to inflict damage to the boss.
After that state has been defeated, the two buds on the side will rotate wildly, occasionally stopping while the flowers change a color, and just like before, attack it if it's your color.

Guardian of Talus Cave
When the battle starts, he'll be frozen, just attack the ice with your sword. After a while, he will become unfrozen. You and your opponents should attack him with the Pegasus Shoes and send him backwards, into the wall of ice. Repeat the process. After a while, he will become faster, and Ice Sicles will drop from the ceiling.
After a while, he will change into another enemy, just attack the bulb that is the same color as your tunic. Beware! Only your friends can see what color your side is. Watch out! If you attack the wrong side, you will get shocked, and loose health, and that's always not good! ;)

Death Mountain Boss
When you first start out, this boss will shoot out colored fire balls. If the color of the fire ball matches your tunic, swing your sword at it, sending it to either the enemy or your friend, who has to swing it in return, sending it back to you or the boss (Fire Ball Tennis). Repeat this process until the boss is defeated. As your amount of attacks increases, the number of times you will have to attack will also increase.

Vaati
When you first start out, he will be an armored wizard riding a tornado, quickly throw bombs into the base of the tornado and detonate them before they are thrown out. Do this several times to cause this phase's defeat.
In the second phase, Vaati will become the previous bosses, but stronger. You will not have to defeat all of them, but you will have to put up a fight. Keep delivering blows until the final one, and save the princess and seal Vaati away into the Four Swords.