The buffer is a mechanic in Super Smash Bros. Brawl, Super Smash Bros. 4, and Super Smash Bros. Ultimate which allows players to successfully input actions before they can actually be executed, causing the inputs to be carried out the first frame possible as soon at the first move or animation is finished. This allows players to have a considerable amount of time to perform actions or techniques which would otherwise require frame-perfect precision, and can be used in combos to minimize the opponent's opportunity to escape from hitstun. Buffer is not a mechanic exclusive in the Super Smash Bros. series, with numerous video games from various genres also having some sort of buffer system (including various traditional fighting games). While buffering has always existed within the Super Smash Bros. series, it did not become a universal mechanic until Brawl and its functionality has changed in each game.
There are negative effects to buffered inputs. Buffering may lead to unintentional attacks that carry out (e.g. attempting to buffer a jab nearby the ledge while shielding, which would result in using a neutral aerial off the stage). This kind of situation can be deadly to characters with laggy aerials, such as Ike, whose recoveries do not provide enough vertical distance to recover after the attack ends. When playing online, the frame delay introduced to stabilize matches can affect buffering windows. When combined with possible Wi-Fi lag caused by a poor connection, unintentional inputs can become significantly more common in online play.
In the original Super Smash Bros., there is no universal buffer system so most actions need to be performed frame perfectly to be performed as quickly as possible. This is often cited as a reason for greater skill and precision in comparison to later games in the series. There are however certain instances where certain actions can be buffered. Some of these actions include:
Much like its predecessor, Super Smash Bros. Melee does not buffer inputs under normal circumstances but there are instances where actions can be buffered. A majority of bufferable actions in the previous game can still be buffered in Melee although there are some changes.
In Super Smash Bros. Brawl
Super Smash Bros. Brawl was the first game in the series to introduce a universal input buffer for basic actions. When the player is performing an animation, there is a window of 10 frames at the end of most moves and animations where the player can buffer any action (including attacks, jumps and dodges). This allows to player to easily perform frame perfect actions without having to frame perfectly time their button presses (giving them 1/6th of a second to perform these actions rather than 1/60th of a second). If the animation is shorter than 10 frames, the player can still buffer actions but they will have less time to do so.
Forward tilts and down tilts (as well as side and down specials without a smash input) require an unusual set of inputs in order to buffer. The player cannot just hold forward or down and press attack to buffer a forward/down tilt in most cases (like they can with an up tilt). They have to input the tilt during the buffer window and then let go of the control stick before the buffer window ends. This makes forward and down tilts harder to buffer than most attacks.
When multiple buttons are pressed, the game will usually buffer the first input pressed (so if the player did a forward smash, a side special and then a spot dodge for example, the game would buffer the forward smash) but there are some instances where the game can buffer multiple inputs. This can result in the player being capable of doing things which would not be possible without buffering. Some examples of this include:
Despite the introduction of a universal buffer mechanic however, there are still multiple instances where the player cannot buffer either a specific action or any action. Instances where this is the case include:
In Super Smash Bros. 4
In Super Smash Bros. 4, the universal buffer system returns, albeit with some adjustments. There is now a hierarchy of moves that will come out when multiple inputs are pressed at the same time/during the buffer window. Special moves have the highest priority, followed by shields, attacks, jumps, and stick inputs, in that order. For ledge options, ledge jumping has the highest priority, followed by ledge attacking and ledge rolling. This hierarchy is the reason why buffering both a control stick input and a button input at the same time (or multiple button inputs) is impossible and thus, a common problem when trying to perform moves like dash attack or dash grab out of shield. This also means that multiple actions which could be buffered in Brawl (like an immediate double jump aerial or a dash attack) can no longer be buffered.
The strange buffer issue forward tilts, down tilts/specials and side specials had in Brawl has been fixed, allowing these moves to be buffered like any other move. This issue does still exist with down tilts/specials when performing a soft or hard landing however although like in Brawl, the player can still buffer these actions by letting go of the control stick before the landing animation ends.
Most of the actions which cannot be buffered in Brawl still cannot be buffered in Smash 4 although the player can now buffer actions out of hitstun unlike in Brawl. The issue where moves could not be buffered out of a down tilt with no interruptible frames has also been fixed.
In Super Smash Bros. Ultimate
While Ultimate retains the buffering system from Smash 4 (albeit with the window reduced to 9 frames), it also introduces a second universal buffering system: holding an input through the end of a previous move's animation will now cause the held input to be buffered. This type of buffering has always existed for actions such as walking and shielding but Ultimate makes it a universal mechanic for any animation. The input can be made as early as desired, but must be held until the standard 9 frame buffer window is reached. For example, holding the forward smash input the entire time after using a recovery onstage will result in it charging when the character lands. This can also cause other negative side effects while bringing its own advantages, such as making buffered airdodges more likely, but also making the online mode have more consistency in inputs.