Defeating Ganons Second Form Easliy:

When you escape Ganons tower with Zelda, right before you leave the level a cutscene will appear showing Ganon transform into his second form. When the fight begins he will immediately knock the Master Sword out of your hands. At this point you should have max deku nuts, the big Goron sword, two fairies and two restore magic potions. Ganon attacks by swing his arms at you kind of like the wolfos except he does't turn when he's finished. To stun him use a light arrow on him then pull out the big Goron sword and hack away at his tail. (Don't believe what other walkthroughs tell you if you have the true big Goron sword it will damage him, even the Deku nuts can damage him if thrown right. Halfway through the fight Ganons forcefield will go down and you can pick up the master sword. He will get smart to your bow attacks and will maneuver them so you give the bow to Zelda. Zelda will shoot at him and let you hit him about three times then he will start to dodge those, when he does switch to the mirror shield so Zelda can reflect the arrows energy off of you. Ganon should fall to his knees and Zelda will tell you to move in for the final blow. If you need hearts or magic lure Ganon over to one of the boulders from the tower and let him smash them.