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 attack with the electric effect such as Captain Falcon's Knee Smash and Samus's Charge Shot (fully charged) have a very long and noticeable hitstun..
Attacks with notable hitstun
These are moves that are notable to start combos due to their noticeably high hitstun.
- Captain Falcons Down Tilt - Captain Falcon thrusts his legs. This move has notable hitstun and can easily set up an Uair or a Knee.
- Sakis Forward Aerial - Saki swings his sword horizontally. This Fair is very similar to Marth's Fair from Melee and Brawl.
Confusion with Hitlag
Hitstun is not to be confused with hitlag, which is the brief pause that occurs when a player is hit by an attack. During this pause, both the player who is attacking and his/her target freeze in place to emphasize the force of the hit. Moves with notable hitlag include Captain Falcon 's Knee of Justice, Knuckles 's fully charged Spin Punch, and Pikachu 's Forward Smash. Hitlag has no effect on gameplay other than the small pause created and is usually a nearly imperceptible effect.