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/knockback. 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 effect, allowing the possibility of near-infinite combos. Bowser won't flinch when hit by a weak attack.

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 d-tilt from far enough).
• Mr. Game & Watch's Judge when holding a card of 1
• 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.

Ways to prevent/reduce flinching

• Metal Box
• Super Mushroom
• Starman
• Certain Stickers (only in The Subspace Emissary)
• 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 was extremely high. This meant 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 Melee, hitstun was lowered slightly, but wasn't lowered so much that it didn't allow for any combos, because it still allowed for many, such as the Ken combo. 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 operated mostly on combo ability.

In Brawl, hitstun was severely lowered, something that the game is often criticized for by pro Smashers. 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 Dair to Uair tactics, Sheik's Forward Tilt Lock, Meta Knight's Uair 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.

For the 3DS/Wii U versions, Masahiro Sakurai has revealed that occasionally large characters, such as Bowser, will not flinch from small blows, allowing them to charge up attacks even while being attacked.