Demon King Ganondorf

The approach is a crowd of monsters in the dark. Spend your ordinary fused weapons here and save the Master Sword's energy for him. His swings can be dodged into a flurry rush. He also creates copies and gloom attacks that blacken hearts even when the hit looks small. Eat a sundelion meal between phases, not after the bar is already empty. A dark heart is a heart you do not have.

When he loses the warrior form, he takes the secret stone and becomes the Demon Dragon. Skydiving onto that dragon is the last phase. Destroy the weak points along the body, then the stone at the head. The sages fight beside you and can be knocked down. The fight can still be finished if one of them falls. Landing on the dragon and staying on the weak point matters more than chasing every add.

Pull the Master Sword from the Light Dragon before you go, if the dragon tears are done. It is the weapon this fight is built around, and it comes back after it rests. A few sunny meals, a stack of bomb flowers, and your best bow cover the crowd on the way in. Gloom weapons from Phantom Ganon will hurt you while you hold them, so they are a backup, not the plan.

The four regional sages, and Mineru if you have built her body, appear in the fight and make the crowd shorter. You can walk in without all of them, and the warrior phase simply lasts longer. Lookout Landing is the last safe pot and bed. Cook there, sleep there, and do not open the descent with a bar of black hearts left over from a Gloom Spawn on the surface.