Boost grabbing is a technique in which the momentum from a character's dash attack is transferred into a dash grab (or a pivot grab), which can result in a longer-ranged dash/pivot grab. Introduced in Super Smash Bros. Melee and retained in every game since, the boost grab is a useful form of dash attack canceling, as it cancels the dash attack for a grab, which can lead to more range on the grab depending on the character. As some characters also make their dash attack sounds while performing a boost grab, boost grabbing can also act as a mindgame.
Performing a boost grab
The technique is made possible by exploiting a window for performing a grab during a dash attack. To perform the boost grab, the player must first dash and then press the attack button while dashing to perform a dash attack. The player then has to press the grab button immediately within the first few frames of the dash attack, with the exact window varying between games. If done correctly, the dash attack will be cancelled and the player will instead perform a dash grab. Some characters will travel more distance when using a boost grab, some characters will travel a similar distance and some will travel less distance.
Some characters make sound effects when they perform a dash attack, such as Fox, Luigi, and Snake. As a result, some players recommend learning boost grabbing with these characters, as to learn the precise timing of a boost grab.
In Super Smash Bros. Melee there is a three frame window where a dash attack can be canceled into a dash grab (as the first frame of the dash attack cannot be canceled). While it is a universal technique, only Sheik, Fox, Falco, and Marth benefit from it as they are the only characters who gain a significant range increase when performing it. Sheik notably benefits from boost grabbing, as it almost triples her grab range.
In Super Smash Bros. Brawl, the window for boost grabbing has been reduced to two frames, making it more difficult to perform than in Melee. The technique is still useful however with Snake, driving the most use out of it, as it not only grants significant distance, but it can assist him with tech chasing with his down throw and can allow him to more easily regrab characters out of grab releases.
It is also now possible to perform boost pivot grabs by inputting a pivot grab during the dash attack. This can be beneficial for some characters with Falco noticeably benefitting from the technique as it not only greatly increases his pivot grab's range but it also aids his chain grabbing potential as he can use a boost pivot grab to reverse the direction of his chain grab (which he cannot do with a normal pivot grab). It can even be beneficial if it covers less range than a normal pivot grab. Captain Falcon for example travels a very long distance when using a pivot grab to the point where it can often miss at close range. If Captain Falcon "boost" pivot grabs however, he will travel much less distance, allowing him to land his pivot grab in situations where it would have missed otherwise.
The boost grab returns in Super Smash Bros. 4. For most characters, the grab range benefit it gives is minuscule at best, which overall limits its usefulness. However, Rosalina & Luma have a unique use for boost grabbing however as if Rosalina performs a boost grab, she will dash grab, while Luma still performs the dash attack. This makes the grab safer, makes it harder to avoid (as Luma's dash attack comes out before the grab) and also means they can potentially deal some damage upon landing the grab.
The window to perform a boost grab in Super Smash Bros. Ultimate has been increased to three frames, much like in Melee. Many of the characters who benefitted from the usage of boost grabbing in all earlier Smash games (such as Snake in Brawl and Rosalina & Luma in Smash 4), still benefit from it.