A counterattack is a type of special move. On use, they put the user into a shield-like state followed by a sizable period of lag. Should any normally blockable attack hit the user during these guard frames, the attack will be blocked and the user will automatically use an attack of their own, presumably hitting whoever was attacking unless it was a projectile, or some other attack that outranges the counter. Some counterattacks do more damage when they activate against a stronger attack, with knockback scaling to match the damage, while some deal a fixed amount of damage. Counterattacks usually activate fast enough that its impossible for the victim to shield the retaliating hit, although the attack itself can usually be blocked; there are a few exceptions, such as Shulk's Vision, which is unblockable.
A correctly-timed counterattack can tilt the momentum of a match towards the user, though as they are generally not effective on reaction, reading the opponent is crucial. Simply using counters repeatedly in hopes of getting one in will result in a competent opponent waiting until the move's lag to attack, or simply using an uncounterable grab.
While unblockable attacks cannot be countered (except Witch Time), as previously mentioned, depending on the move, the user may still not take damage due to the initial invincibility frames. Unlike reflectors, there is no limit to how much damage can be countered, though in Smash 4, there is a cap on how much damage a counterattack can inflict, at 50%. The only exception is Shulk's Vision; its damage cap can be raised or lowered depending on which Monado Art is currently active.
Counterattacks were introduced in Melee, with Marth's and Roy's down specials and Peach's neutral special. In Smash 4, counterattacks cannot counter some explosive attacks such as Link's Bombs and Steel Diver missiles, instead giving the user protection against them during the counter frames. Stronger explosions can be countered, however, such as the Bob-omb. Up until Smash 4, counterattacks did not have any special aesthetics upon countering; in Smash 4 most counterattacks gain a unique particle effect once the counter activates: a wave quickly appears, representing a heartbeat. This applies to all counterattacks lacking a separate particle effect, namely the entire cast that possesses a counterattack save for Greninja and Lucario. Each counterattack's heartbeat wave colour varies: Palutena's is blue, Little Mac's is red, and so on. 16 characters can now utilize a counter in Smash 4, 12 of which are available by default, and the game has become somewhat notorious for the high number of counters added to the game compared to Brawl (which had 4 counters).
List of counterattacks
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