Handicap

A handicap, in the  series, is a feature that helps to provide balance in matches between human players of different skill levels. Handicap options for a match can be set to On, Off, or Auto - On allows each player to set their own handicap, Off disables the feature, and Auto dynamically adjusts players' handicaps based on who wins each match.

In Super Smash Bros. and Super Smash Bros. Melee
In the first two games of the series, handicap affects the knockback done by attacks, with no effect on the characters' damage percentages.

When the option is set to On, each player's handicap can be set to a value between 1 and 9, with 9 being normal in Super Smash Bros., and 5 being normal in Melee. A character with a handicap of 1 will have drastically weakened attacks in terms of knockback, and suffer much more knockback from opponents' attacks. At the other end of the spectrum, a character with a handicap of 9 will do substantially more knockback than usual, and take very little knockback from opponents. It is unclear what the technical meaning of the number is.

Because the computer players in Super Smash Bros. have their difficulty level meter over their handicap meter, their handicap will be the same as their CPU level (which is also numbers from 1 to 9). In Melee, they are instead properly given two independent meters for both CPU level and handicap.

When the option is set to Auto, each player's handicap is initially set to the same value (5) and cannot be manually adjusted. Instead, the values are automatically adjusted based on the results of each match played. When a player wins a match, their handicap is lowered by 1, thereby making them easier to knock off the stage in the next match. Conversely, the handicap of the player who loses the match will be raised by 1. In matches with more than two players, only the handicaps of the first and last place players will be adjusted.

Melee data and handicap 8 error
Earlier versions of Melee had a programming error with the handicap system, as decoded by the debug menu The ratios all follow an exponential function, and the offensive and defensive ratios are inverses of each other - with the exception of the handicap 8 defensive ratio, which is completely out of line with both patterns. As a result, a handicap 8 character has significantly more knockback resistance than a handicap 9. The cause of this discrepancy is unknown, and it was fixed in a later revision by changing the 0.52 to 1.08.

In Super Smash Bros. Brawl and Super Smash Bros. 4
In Brawl, unlike its predecessors, the handicap feature does not affect knockback. Instead, handicaps now solely determine the initial damage percentage with which each character begins matches (and respawns after a KO). Rather than using a scale of 1 to 9, each player's desired percentage can be chosen from a menu, in 10% increments. Players may, as always, begin the match with 0%, or raise the percentage up to 300%, which is also the starting percentage for Sudden Death and Super Sudden Death.

When the Handicap is set to Auto, all players will start with 0%. Every time a player wins, they gain 20% handicap. Every other player will lose 10% handicap, assuming that they have 10% or more already.

Smash 4s handicap works identically to Brawls, although it is not always in increments of 10%: it now skips from 60% to 80%, then 100%, 125%, 150%, 200%, and 300%. Due to the new rage effect working depending on damage, players can also use handicaps to grant themselves the effect and deal more knockback with their own attacks.

In SSB4, the maximum percentage a player can begin a battle/stock at, with the aid of customs, is 420%.

In Super Smash Bros. Ultimate
The handicap option in Ultimate functions the same as Smash 4, and enables setting a starting damage percentage for each player.

A new option, called Custom Balance, applies (non-damage percentage) handicaps to individual fighters rather than players. On the Custom Balance menu, each character can be assigned a persistent value between -3 and +3, representing damage modifiers of up to +/-0.3x. These values are only applied when the Custom Balance rule option is enabled, which is not available in multi-console wireless or online play, or in single player modes aside from Training Mode. Crucially, the altered damage outputs of the fighters is factored in to the knockback formula, unlike with Spirits.