Stun

Mario stunned by Wario. A Gooey Bomb has been placed on him as well.

Ness in a state of dizziness in the original game.

Being stunned (known as dizziness in Brawl) is a special condition that leaves a character immobile for a short period of time. The most common way a character can become stunned is by having their shield broken. When a character is stunned, they will be dazed for a few seconds and won't be able to move or attack. The only ways for a character to snap out of this condition is through an attack of another character (unless the attack does not cause flinching), waiting out the condition, or by button mashing.

Unlike most other status effects, characters can escape being stunned easier at higher percentages (whereas sleep, for example, lasts longer at higher percentages).

The sound effect of being stunned is a cartoony tweet sound effect that loops until the condition is stopped immediately. This sound effect debuted in Melee. In Brawl, the sound was less cartoony than in SSBM. The sound effect does not play if the character has taken very heavy damage.

Causes of Stunning

• Shield shattering - When the character's Shield shatters from overuse of it, the character will be stunned for a short period of time.
• Reflector shattering - Reflectors slightly increase the power of what they reflect. If the same thing is reflected multiple times, the Reflector can be overloaded and shatter like a shield. This is absent in Brawl, where instead of shattering the reflector will just fail to reflect the attack, and the user will be damaged and knocked back.
• Disable - Mewtwo's Disable causes stunning if eye contact is made with it.
• Deku Nut - When the Deku Nut is broken, all the grounded characters in the blast radius will be stunned. The Deku Nut will break on its own when not used for a period of time.
• Weavile's False Swipe - Weavile will slash across the stage using its False Swipe move. Any grounded character that makes contact with Weavile's False Swipe will be stunned momentarily. If the player is caught in the attack, it can very difficult to avoid being hit again.
• Wario Waft - When Wario-Man does a barely charged Waft, it briefly stuns opponents.
• Negative Zone - Among other things, exposure to Luigi's Negative Zone can stun opponents. If the character is in mid-air while the Final Smash is active, they will fall back to the ground and will be stunned (thus, being automatically done with a Shield break).

Trivia

• In Brawl, Bowser is the only character to lack the tweeting sound effect while he is stunned.