Odolwa: Recommended Item: Bunny Hood
Whenever he dances go up yo him and use spin attack or jump attack.
Goht: Recommended Item: Fire Arrows
Go to where Goht cant get you. Shoot Fire Arrows at him until sparks come from him then chase him with the Goron Mask.
Gyorg: Recommended Item: Zora Mask/Arrows
Shoot a arrow or use the Zora Boomerang to stun him. Then jump into the water and attack his face. (might need a fairy or 2)
Twinmold: Recommended Item: Giants Mask
Get unlimited magic from the Milk Bar. (Chateu 200 Rupees) Wear the Giants Mask in the boss room. Attack either its head or tail.
Majora's Mask: Recommended Item: Fierce Deity Mask
Clear all four Mini-Dungeons on the moon. Then talk to the kid with Majora's Mask on. He will give you the Fierce Deity Mask. I would get Unlimited Magic for Majora's Mask because you can attack from a distance. Which makes it so much easier. =D