ChangelingChangeling is a characteristic-defining ability. “Changeling” means “This object is every creature type.” This ability works everywhere, even outside the game. See rule 604.3. (CR 702.73) (This card is every creature type.)
FlashFlash is a static ability that functions in any zone from which you could play the card it’s on. “Flash” means “You may play this card any time you could cast an instant.”
Multiple instances of flash on the same object are redundant. (CR 702.8)
FlyingFlying 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. (CR 702.9)
When this creature enters, return up to one other target creature you control to its owner's hand.