Flinch

Pit flinching by Zero Suit Samus' Plasma Whip

Flinching, also called Hitstun, is what happens to a character when they are hit by an attack. The character will be stunned for a very short period of time, usually just enough to interrupt any attacks or movements. Specifically, flinching is basically an extremely small amount of hitstun. There are certain attacks that do not cause flinching, and ways for a character to avoid flinching. Some attacks cause flinching without any knockback whatsoever. It is used for combos in all 3 smash games. Some powerful electric attacks such as Knee Smash, Samus's Charge Shot (fully charged), and Zelda's Lightning Kicks have a very long and noticeable hitstun, and using a Timer can amplify the affect, allowing the possibility of near-infinite combos.

Attacks that do not cause flinching

• Fox's Blaster (except in Super Smash Bros.)
• Mario's F.L.U.D.D. (no damage)
• Dr. Mario's and Mario's Cape
• Squirtle's charged Water Gun (no damage)
• Link's Gale Boomerang (on the return) (no damage)
• Ness's PSI Magnet (when finishing the attack) (no damage)
• Snake's thrown Grenade (not the explosion)
• Olimar's Pikmin when latched on
• Some of Olimar's non Pikmin based attacks; when hit only with the antenna (such as his down tilt from far enough).
• Mr. Game & Watch's Judge when holding a card of 1
• The flame of Charizard's forward aerial
• The rain that occurs in the "Kitty Cover" game in the stage WarioWare, Inc.
• Glancing Blows (no damage)
• Kyogre (no damage from its Hydro Pump)
• The Bulborb attack from Olimar's Final Smash, End of Day.

Attacks that cause flinching with no knockback

• First hit of Lucario's Down aerial
• Most first or first and second hit of jabs.
• First three hits of Snake's Neutral aerial
• First three hits of Snake's Down aerial
• First hit of Snake's Forward tilt (on grounded characters)
• First hit of R.O.B.'s up tilt.
• First four hits of R.O.B.'s down smash.
• First four hits of R.O.B.'s up aerial.
• Luigi's Super Jump Punch (in Melee and Brawl, non-sweetspotted)
• Falco's Blaster
• Fox's Blaster (SSB only)
• Smart Bomb (only when it does the echoing sound)
• Wolf's Blaster (only the laser)
• Diddy's first hit of forward smash

Ways to prevent/reduce flinching

• Metal Box
• Super Mushroom
• Starman
• Certain Stickers (only in Adventure Mode: The Subspace Emissary and Boss Battles Mode in Brawl)
• Any moves that offer knockback resistance.
• Using an aerial attack or air dodge (Brawl only and advisable to use fastest aerial in a character's arsenal)

In the original Super Smash Bros., hitstun is extremely high. This means that this game had the most extreme and arguably best combos in the series, allowing almost every character to have a 0-death combo.

In Super Smash Bros. Melee, hitstun is lowered slightly, but is not lowered the degree that it did not allow any combos. The majority of characters have some combos, but 0-deaths are rare (and those that exist require extremely quick fingers and lots of technical skill to utilize). The Top, High, and Middle tiers all operates mostly on combo ability.

In Super Smash Bros. Brawl, hitstun is severely lowered. The opponent suffers very little stun after being hit, and air dodging decreases it even further. Thus, the game has hardly any real combos. Some exceptions are Peach, Sheik, Kirby, and Meta Knight, who all have fast enough moves (or a select few, in Peach's case) to combo fairly well. Notable combos include Peach's down aerial to up aerial tactics, Sheik's Forward Tilt Lock, Meta Knight's up aerial chaining, and Kirby's Forward Throw combos. However, these can be DI'd out of with near perfect SDI, and the combos rarely exceed two or three hits.