Can someone give tips on defeating a boss on Kingdom Hearts 358/2 days?

start of the battle, immediately Lock-On to the Heartless.attack whenever possible.The best time to strike is as the Ruler is turning.After sustaining about half a bar of damage, a segment of the Ruler of the Sky's tail will break. At this point, the Ruler of the Sky will enter a berserk state and glow with a pink aura. It will also release a burst of energy as it begins its berserk attack. The Ruler of the Sky will begin swooping back and forth in an attempt to hit you. Occasionally it will release a homing ball of energy when it begins its rush. If you fly too close to the water, it will drop homing energy balls in rapid succession. Try to dodge downwards and to the side to avoid its rush without going too low. If you do go low, use the terrain to your advantage to avoid the energy spheres.