What are blue yellow red white and black flute used for in Pokemon emerald?

Red Flute heals attraction.

Yellow heals confusion.

Blue heals sleep.

Black Flute makes wild Pokemon encounters less common.

White Flute makes wild Pokemon encounters more common.

Red, Yellow, and Blue are all extremely useful during the game because they do not go away once you use them. Unfortunately, they can only be used from your bag, so you cannot use them during battle tower, etc.