Chaos Imps

Flying is an evasion ability.

A creature with flying can’t be blocked except by creatures with flying and/or reach. A creature with flying can block a creature with or without flying. (See rule 509, “Declare Blockers Step,” and rule 702.17, “Reach.”)

Multiple instances of flying on the same creature are redundant.

Unleash is a keyword that represents two static abilities. “Unleash” means “You may have this permanent enter with an additional +1/+1 counter on it” and “This permanent can’t block as long as it has a +1/+1 counter on it.”