Hitstun

Hitstun is a phenomenon in the  series and Fraymakers in which a character is mostly inactionable for a set period of time after being hit by an attack. In the original Super Smash Flash, each character has a stat with a set that dictates how long their hitstun lasts when hit by any attack. In Super Smash Flash 2 and Fraymakers, hitstun duration is instead a stat specific to the attacks themselves.

Hitstun in SSF2 and Fraymakers begins immediately after hitlag ends, and characters are only able to use directional influence or tech during this time. It normally scales with knockback, with SSF2 having a knockback multiplier of 0.4, though certain attacks instead have a set amount of hitstun they will always inflict.

Hitstun is an essential component of combos, as the basis of a combo is to have opponents be unable to interrupt or prevent the player's combo from happening. Thus, moves with higher hitstun have more potential for starting or extending combos. A combo that does not allow the opponent to escape from hitstun is also known as a true combo.

Excluding teching, hitstun normally cannot be canceled in any way. The exception to this is meteor canceling in SSF2, in which the player can cancel their reeling animation with a midair jump or up special move when hit by a meteor smash.

Flinching
In SSF2 and Fraymakers, flinching always occurs alongside hitlag, and characters may continue flinching during hitstun caused by an attack that deals low knockback. This often happens when characters are at low damages. In SSF, characters will flinch for a set time regardless of knockback amount. In each game, characters revert to their falling animations once the knockback diminishes and this animation ends.

Reeling
Reeling is an animation in SSF2 and Fraymakers that plays after flinching when hit by an attack that deals high knockback. This often happens when characters are at high damages. Once the knockback diminishes and the character slows down, both reeling and hitstun end, and tumbling begins.