A stall-then-fall is a type of aerial maneuver in all installments of the Super Smash Bros. series. Types of stall-then-falls vary from kicks to hip drops. No matter the type, all stall-then-falls are similar in function. Stall-then-fall moves come in 2 types, aerials and special moves. Stall-then-fall specials exist in all games of the series, and stall-then-fall aerial attacks have existed since Super Smash Bros. Brawl.
The attack is as simple as the name: the character pauses briefly in the air, then rockets downward, usually with a kick. The downward falling speed can be much greater than the character's usual falling speed, even while fast falling. Most of these attacks launch the character diagonally forward and downwards, but a few of them (Toon Link's, Mr. Game & Watch's, Bowser's, Kirby's, Yoshi's, Ridley's, and Banjo & Kazooie's) do not, instead launching straight downwards or allowing the direction to be controlled (Mr. Game & Watch and Bowser's down aerial in Super Smash Bros. 4).
If the character performing the move hits the stage while the attack is still being executed, there is typically a fairly large landing lag with most of them. However, some of these moves have an additional hitbox upon hitting the ground, creating a shockwave effect that extends a short distance to either side of the character.
Aerial stall-then-fall attacks have their downwards movement disabled if the character attempts to use such a move to cancel hitstun from vertical knockback they have recently received, or if they are used while there is any residual knockback from attacks that cause hitstun, even after the hitstun would have ended. This behaviour originates from Brawl, where aerial attacks can be used to cancel hitstun, presumably in order to prevent this from being exploited to avoid being KOed vertically, although this behaviour extends to aerials which push opponents upwards as well, such as Fox's forward aerial. Starting in the 4.0.0 update for Ultimate, many stall-then-fall aerials do not have this property anymore, however removing it requires hard-coding, and they will still exhibit this behaviour by default, if not programmed not to do so. Notably, since residual knockback stacks with the momentum from the aerial, as it does will fall and air speeds, and as such the initial stall can cause the fighter to be boosted upwards, and the fall will be slower to begin with.
All aerial stall-then-falls are momentum based, meaning that they simply add a large amount of downwards momentum to a fighter, and thus the downwards momentum can persist after the move ends, depending on a fighter's vertical air friction. This also means that, like special moves, and unlike other ground moves like tilts and rolls, the speed granted by stall-then-fall aerials ignores size changes, but may be affected by stat changes, such as the stalling portion of Bowser's down aerial gaining more height in light gravity, and less height in heavy gravity.
Special move stall-then-falls behave like any other special move which moves a fighter. They typically use scripted motion rather than adding momentum, and they will not have their movement disabled by residual knockback, rather they will always stack with it. Some such specials also move horizontally when used on the ground, examples of this include the Falcon Kick, Wizard's Foot and Power Thrust.
If one of the down aerial stall-then-fall attacks is used immediately after beginning to fall through a platform, the stall will cause the character to move slightly above the platform, so that they fall immediately directly on to it. This is somewhat useful with Toon Link and Mr. Game & Watch, who have the shortest landing lags on their stall-then-fall aerials, and can use this technique to land several quick hits.
Certain stall-then-fall aerials will cause the user to skid down slopes a bit, mainly Toon Link's and Mr. Game & Watch's. Depending on the steepness of the slope, this can be a tiny distance or a huge one, and at steep slopes, the character slides a large distance at a speed that is often faster than their dash. This could be used to keep an opponent from taking advantage of the long landing lag, and also for mindgames.
Stall-then-falls are useful for sweet-spotting the edge. The player can use the attack in midair, fall to below the level of the edge, and use their midair jump or up special move. They must be very high above the bottom blast line to avoid a self-destruct.
Extra jump (Melee only)
Some characters are vulnerable to juggling due to floatiness, such as Kirby and Toon Link. Having a stall-then-fall move allows the character to be less vulnerable to juggling due to the increased falling speed, which will make it difficult for the juggler to respond quickly.
Stall-then-falls have a long duration. If used while off of the stage, they can result in a self-destruct. Therefore, it is advisable to not use the attack off the edge at all (except for sweet-spotting - see above).
Characters with stall-then-fall attacks