Knockback

Knockback is the distance a character flies when hit by an attack in the Super Smash Flash series. It is measured in pps, or pixels per second. For example, 's fully charged forward smash in Super Smash Flash 2 does 9 pps of forward knockback to an opponent at 0% damage. A player can avoid receiving knockback when under the effects of invincibility, intangibility, or knockback resistance.

Conditions
This is a list of conditions the knockback of an attack depends on:
 * The current damage of the opponent.
 * The current movement speed of the opponent.
 * The damage dealt by the attack.

If the damage dealt on a character's attack matches the damage given by their, that attack will deal vertical knockback. Every character's up attack deals the same damage as their down aerial. Other attacks will inflict horizontal knockback.

Attacks with horizontal knockback will send enemies 3 knockback units forwards, and one unit upwards (about 18.435°); while attacks with vertical knockback will send enemies one knockback unit downwards (if said attack is a down aerial) or upwards (if said attack is not a down aerial). Attacks with vertical knockback will take the opponent's current movement speed into consideration when calculating the total knockback, sometimes resulting in an instant-KO.

Conditions
This is a list of conditions the knockback of an attack depends on:
 * The current damage of the opponent.
 * The weight of the opponent.
 * The damage, base knockback, and knockback scaling of the move used.
 * Whether the opponent is charging a smash attack.
 * The launch rate of the match.
 * The damage ratio of the match, which is normally 1 outside of certain Solo modes.

Knockback values
Each hitbox of a move has two knockback values: a base knockback and a knockback scaling (also known as knockback growth).

Base knockback, referred to as power in the code, is the minimum amount of knockback that an attack can deliver (in normal circumstances), and knockback scaling is a factor that controls how much knockback increases as damage increases. Moves with high base knockback deal high knockback under any circumstances, such as the swing of the Home-Run Bat. They additionally tend to be more effective at KOing when less knockback is needed (ex. light characters who are near the ledge or when an opponent is handicapped to sustain more knockback).

On the other hand, moves with high knockback scaling take less damage to reach KO potential, such as 's forward smash. They additionally tend to be more effective at KOing when the opponent requires more knockback to be KO'd (such as against heavier characters, when far away from a stage's blast line, or when an opponent is handicapped to sustain less knockback). Techniques such as Directional influence and Momentum canceling who help extend a players survival becomes less effective the stronger an attack's knockback scaling is.

Set knockback
Set knockback, sometimes referred to fixed knockback, is a property of some attacks where the knockback dealt by the attack is static. As such, it does not depend on the opponent's percentage. Some moves also deal set knockback based on a character's weight, called weight knockback.

List of set knockback attacks

 * Many s.
 * 's neutral aerial and forward aerial (weak hits).
 * 's down smash, and.
 * 's up smash (first hit).
 * 's forward smash (weak hits), and up smash (first hit).
 * 's up aerial (first hit) and.
 * 's.
 * 's down smash (weak hits).
 * 's down aerial and Vine.
 * 's dash attack (weak hits), down aerial, and Inhale.
 * 's down aerial (weak hits).
 * 's up throw, (weak hit), dash attack (weak hits),and.
 * 's down aerial,, and Cape.
 * 's Shadow Clone Slash.
 * 's up throw.
 * 's forward aerial (weak hits), and Quick Attack.
 * ' forward aerial and up aerial (weak hits), and forward smash (first hit).
 * 's up smash (first hit).
 * 's up smash and down smash (weak hits).
 * 's up aerial (first hit), and.
 * 's down smash, and Chomp.
 * 's up smash (weak hits).

No knockback
No knockback, as the name says, are attacks that do damage, but deal zero knockback. These attacks are normally used to damage the opponent without making them flinch, but the opponent is still able to move freely while they are being attacked.

List of no knockback attacks

 * 's.
 * 's Mega Buster (level 1, late hit).

Formula
The knockback formula used in Super Smash Flash 2 is similar to the formulas used in the  series. For attacks with no set knockback, the formula is ${[((p ~ + ~ d) ~ \times ~ 0.1 ~ + ~ d ~ \times ~ (p ~ + ~ d)) ~ \times ~ m ~ \times ~ 1.4 ~ \times ~ \frac{200}{w ~ + ~ 100} ~ + ~ 18] ~ \times ~ k ~ \times ~ 0.01 ~ + ~ b}$, where $p$ is the current damage percentage of the opponent, $d$  is the damage the attack deals, $m$  is a multiplier set to 1 by default, $w$  is the weight of the opponent, $k$  is the attack's knockback scaling, and $b$  is the attack's base knockback.

For attacks with set knockback, the formula is instead ${[(s ~ \times ~ 10 ~ \times ~ 0.05 ~ + ~ 1) ~ \times ~ m ~ \times ~ 1.4 ~ \times ~ \frac{200}{w ~ + ~ 100} ~ + ~ 18] ~ \times ~ k ~ \times ~ 0.01 ~ + ~ b}$, where $s$ is the set knockback.

For both formulas, the total knockback is then multiplied by 1.2 if the opponent is charging an attack, and it is finally multiplied by both the launch rate and damage ratio of the match.