Shield (Link)

has his own personal shield that he uses in Super Smash Flash 2 while in battle. If Link stands still or crouches, he will hold his shield directly in front of him, and most projectiles that make contact with it will hit the shield instead of hitting Link, leaving Link unharmed. This will push him back depending on the damage and knockback the projectile would do normally.

However, projectiles must come in contact with the shield for them to be out-prioritized; Link will take damage if the projectile hits his face, feet or back. However, sometimes a projectile will come in contact with the shield and still damage Link.

Origin
Link has carried a shield in almost every The Legend of Zelda game to defend himself against certain attacks, starting with the original The Legend of Zelda. Its particular design in SSF2 is based on that of the Hylian Shield used in The Legend of Zelda: Twilight Princess. The function of the shield varies depending on the game; the shield is often an always-active ability so long as Link is standing or walking, but in certain games it has to be raised manually. In either case, Link must be facing the attack in order to block it, although certain powerful attacks may be too much for the shield and may cause Link to stagger or damage him anyway. Link being able to shift his shield's position by crouching is reminiscent of Zelda II: The Adventure of Link, where Link can either defend his upper body or lower body by standing or crouching.