Invincibility

Invincibility is a state where a hurtbox cannot be attacked or damaged. Attacks will connect, but will not deal damage, knockback, or hitstun, though the attacker will still experience hitlag. Invincibility should not be confused with intangibility or armor, as all three are different mechanics with different effects.

Overview
There are many ways to achieve invincibility in game. The most common way is to respawn, where the player is invincible for a certain amount of time after leaving the revival platform. Certain attacks also have invincibility, some covering the whole body and others only covering certian hitboxes. If a player attacks an opponent while they are invincible, the player will receive the normal amount of hitlag, but the opponent will otherwise be unaffected. Characters who are invincible can still be affected by certain windboxes, as well as Master Giant's grab attack in Smash 4. This can be incredibly useful for the opponent, as they can capitalize on the opponent still being in hitlag and punish them or bait a certain reaction by using an attack with invincibility.

Invincibility does have a somewhat niche downside in that on the Planet Zebes, Brinstar, and Norfair stages, invincible characters will fall straight through the stage's lower hazard, rather than sustaining damage and bouncing back up. They may occasionally also be KO'd if they are standing on the track on Port Town Aero Dive, and both the Melee Mute City and the Smash 3DS Mute City.

In Super Smash Bros. Melee's, invincibility is displayed by affected hurtboxes changing from their usual yellow color to a green color during the invincibility period. A similar feature is present in Super Smash Bros. Ultimate's Training Mode via an invincibility toggle, which causes invincible parts of characters to acquire a green tint.

In Super Smash Bros. Brawl, it is actually possible to hit an opponent normally out of invincibility. If an attack connects while the opponent is invincible and then the invincibility ends while the attacker is still in hitlag, the attack will actually hit the opponent when they become vulnerable due to the hitlag extending the duration of the hitbox. This is only the case in Brawl however, as in every other game the attack will not connect against the opponent once they become vulnerable.

Ultimate introduced, who possesses a counter that staggers any opponent that connects an attack. This can even stagger fully invincible characters, forcing them out of invincibility.

While the differences are seemingly minor, invincibility is different from both intangibility and armor. Intangibility is where a character cannot be hit at all, not even triggering hitlag. Armor is where a character sustains damage, but not knockback. Armor can also sometimes be broken with regular attacks outside of the Sora example.

List of invincible attacks

 * Smash attacks in this table are not charged.
 * All attacks from Smash 4 and Ultimate display invincibility values as of their latest updates.

Trivia

 * If the Shadow Assist Trophy freezes a character while invincible, the character will remain invincible until being unfrozen. This offers some niche competitive strategies where an affected character can achieve invincibility before being frozen and get several seconds where they are unable to receive damage.