With this move, Mega Man activates a moving shield, consisting of four leaves circling around him. These leaves act as one-use damaging barriers, damaging enemies/items and blocking projectiles it comes in contact with at the cost of one leaf, making for a short-term damaging protection around Mega Man. While orbiting Mega Man, leaves may occasionally reverse an opponent, creating an unexpected opening. The shield can also be thrown directly forwards as a potentially long-range attack (it may disappear before the maximum distance is traveled). The Leaf Shield will last either 3 seconds or until all 4 leaves are used up.
Unlike the game of its origin, Mega Man can move around with the shield intact; however, any attack or special input will cause him to throw the shield, so using the move is something of a commitment. An exception is made when Mega Man is holding an item (like his own Metal Blade), as he can still throw the item with the attack button as well as throw the Leaf Shield with the special button. Mega Man can also still shield, grab and pummel while the Leaf Shield is active, and the leaves can deal extra damage to grabbed opponents.
Although its most obvious uses are for extra damage while grabbing and protecting from projectiles, Leaf Shield can also be useful for edgeguarding. If Mega Man stands at the ledge with Leaf Shield active and also uses his standard shield, he can safely threaten recovering opponents. Alternatively, he can jump offstage and try to gimp opponents with the leaves, possibly leading into a footstool jump.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
The Leaf Shield first appeared in Mega Man 2, as the special weapon of Wood Man. These "leaves" are actually shaped pieces of ceratanium, which have been sharpened around the edges. They are able to levitate due to electromagnetism. In Mega Man 2, Mega Man would have to stay still to use this weapon. When staying still, the shield will not leave Mega Man, and will protect him from all attacks. When Mega Man does move, the shield flies off in which ever direction Mega Man started walking in. The Leaf Shield also serves as Air Man's weakness by clogging his fan with the leaves generated. When used on any other boss besides Air Man, the leaves will do 0 damage. In Mega Man 2, the entire Leaf Shield would disappear upon hitting a target, or pierce one with low health. In the Game Boy version, each leaf behaves as its own projectile, much like in Smash Bros..
One of the move's variations, Plant Barrier, first appeared in Mega Man 6, as the power of Plant Man. The "flower petals" are created from condensed energy to protect Mega Man from attacks. It vanishes when hit, but unlike some shield-based powers, it cannot be thrown. It does not vanish if it hits an invulnerable or shielded enemy; however, it can bypass shields and inflict damage. Plant Barrier is the weakness of Tomahawk Man.
The other variation, Skull Barrier, first appeared in Mega Man 4, as the power of Skull Man. The energy shield, which takes the shape of skulls, shuts off when hit. Mega Man can move while the Skull Barrier is active, but he cannot throw this shield. Skull Barrier is the weakness of Dive Man.