Level 1 Boss: Aquamentus
This boss is fairly easy. You'll notice him open his mouth right before he shoots three energy balls at you. During some of the shots he'll take a short break. This is your chance to go up to him and strike him with your sword. If you have your heart containers full, just shoot flying swords at him while you avoid his energy shots. You can also use arrows if you have any, or bombs. After a few hits, he will be defeated and leaves a heart container behind. Pick up the heart container and go into the next room for the first piece of triforce.
Level 2 Boss: Dodongo
You'll need to carry the maximum number of bombs you can for this boss. Bombs are the only thing that can kill the dodongo. This boss is similar to the one from The Legend Of Zelda Ocarina Of Time on the Nintendo Gamecube. As soon as the dodongo makes a turn, place a bomb in his direction. He'll walk up and it will be ingested by him. He will hesitate for a moment and his stomach will expand. Keep doing this and he will be defeated. Just like with every boss in this Zelda game, he will leave a heart container behind and you'll get another piece of triforce.
Level 3 Boss: Manhandla
This boss has four clippers that kind of look like the plant creatures that pop out of the tubes in Super Mario Brothers. You can use your sword to kill off the four clippers, or use bombs. Each time you remove one of the clippers, the boss will speed up. The boss will get faster after each clipper is removed. If you use bombs, it is possible to eliminate more than one clipper at a time. If you place a bomb correctly, you can remove two or three clippers, or even defeat the boss completely if you remove all four with a bomb. Use bombs with a combination of sword strikes to get rid of this boss quickly. If you use a white sword, you can eliminate a clipper with two strikes. It will take four strikes if you use the wooden sword. You can find out how to get the white sword, in the white sword guide I've written that is on this website.
Level 4 Boss: Two Headed Gleeok
This boss is another easy one to beat. The two heads will throw energy balls at you but all you need to do it keep striking the heads with your sword. If you have flying swords just keep using them until you defeat the boss. After you finish one head, it will fly around and shoot energy balls at you. You can't damage the flying head so ignore it and keep shooting or striking the other head on the boss with your sword. Eventually, you'll defeat him and get the heart container and triforce piece.
Level 5 Boss: Digdogger
As soon as you enter the boss chamber use the recorder whistle you found. This will shrink the boss to a smaller size. It will speed up and start moving around the room fast. Try to hit it with bombs and strike it with your sword. This boss is much easier if you have the Magical sword. This is all you need to do in order to defeat the boss.
Level 6 Boss: Gohma
This boss is also similar to the spider boss seen in the Deku tree in The Legend Of Zelda Ocarina Of Time. This boss has one eye in the middle and during the fight, the eye stays shut most of the time. For a very short while, Gohma will open its eye up. This is your opportunity to strike a blow to the boss. You can't use your sword for this. Gohma is immune to your sword strikes. The only weapon that will penetrate the eye, is Link's arrow. You can stand in doorways to help avoid the energy shots being blasted at you. When the eye opens, fire an arrow, and you'll defeat this boss.
Level 7 Boss: Aquamentus
In a strange twist of fate, level seven is very difficult to go through but when you get to the boss, you find out it's the same boss from the first level. This boss is no more difficult than the one from the first level. It's an exact duplicate. Just use the same techniques from the first boss encounter, to complete level seven.
Level 8 Boss: Four Headed Gleeok
This boss has the same strategy as the first Gleeok boss. Keep hitting the boss heads until they start flying. Each head you defeat will start flying around the room and will shoot energy balls at you. You cannot inflict damage on the flying heads. Just keep hitting the heads on the boss. If you have flying swords, it's easy to eliminate at least two of the heads rather quickly. Keep striking until you've defeated the last head.
Level 9 Boss: Ganon
Ganon is fast and easy to defeat. You'll need the silver arrows in order to defeat him. Having the red ring is also very helpful in this battle. The red ring makes your defense much more stronger. There are energy shots being fired at you from statues in the room, as well as from Ganon. So the red ring really can help you win this battle. Ganon is invisible during this battle, so keep changing directions and striking your sword.
You'll eventually hit him. During the first two hits Ganon will turn brown. The third sword strike will turn him gray. Strike him with a silver arrow immediately. He will turn to dust and leave the triforce of power behind. Head into the next room to rescue Princess Zelda. You have now beat the first quest in the Nintendo Legend Of Zelda game.