Answer:
The more holes you cover the lower it goes.
A time when they're green. A time when they're brown. But both of these times, cause me to frown. But just in between, for a very short while. They're perfect and yellow. And cause me to smile.
I'm light as a feather, yet the strongest man can't hold me for more than 5 minutes.
I make you weak at the worst of all times. I keep you safe, I keep you fine. I make your hands sweat. And your heart grow cold. I visit the weak, but seldom the bold.
I can sizzle like bacon, I am made with an egg. I have plenty of backbone, but lack a good leg. I peel layers like onions, but still remain whole. I can be long, like a flagpole, yet fit in a hole.
Special abilities and brightly colored underwear are all you need to be one of these.