Quick Attack cancel
Quick Attack Canceling, abbreviated as QAC and also known as QuACking, is a technique usable by Pikachu in Super Smash Bros. Brawl. It involves using Quick Attack into the ground and jumping (or dropping if aimed into a soft platform) to cancel the lag at the end of the momentum, allowing Pikachu to approach very quickly. This variant of the technique is only possible to its full extent in Brawl although in Super Smash Bros. 4, Pikachu can still perform the technique on slopes. Pikachu can also cancel Quick Attack by edge canceling, which works in all games up to Super Smash Bros. 4.
How it works
When Pikachu normally Quick Attacks in Brawl and touches the ground, it goes into its helpless landing animation. This occurs when Pikachu Quick Attacks horizontally on the ground or when it lands at any point after the Quick Attack dash.
If Pikachu quick attacks into the ground before the dash's animation has ended however, Pikachu will not go into its helpless landing animation once the animation is over. Instead, Pikachu is put into an animation transition frame, where Pikachu is considered airborne but it is also touching the ground. After this frame, Pikachu will enter its normal landing animation with Recovery Carryover Lag. Pikachu is actionable during this one animation transition frame, with Quick Attack Canceling evolving around Pikachu acting out of this frame to avoid landing. When Pikachu is in this frame, it can jump, use its aerials (with Pikachu being able to perform an instant landing down aerial), air dodge, use its specials (including Quick Attack) or drop through platforms. This can be performed with both Quick Attack dashes so in a situation where Pikachu cannot Quick Attack cancel with the first dash, Pikachu can use the second dash
Pikachu's aerials and air dodge without jumping (outside of down aerial) are practically useless as Pikachu as Pikachu is only in the air for one frame, preventing them from coming out. Neutral aerial even gives Pikachu more landing lag than it already would have due to the aerial lacking an initial auto-cancel window (combined with Pikachu having RCO lag). Down aerial can be useful on its own as if Pikachu uses down aerial, it will immediately go into the move's landing animation which has a hitbox although this is risky due to down aerial's extreme landing lag. Dropping through platforms can be useful but it is naturally situational.
The most useful option however is double jumping. Double jumping naturally gives Pikachu instant access to all of its aerials and specials. Once Pikachu has performed a QAC, it can Quick Attack into the ground again (this does not require a double jump) to perform another QAC, which can be performed repeatedly as many times as the player desires.
The move is essentially a form of the Second Jump Recovery technique, working in the same way. The main difference with a regular SJR however is that with a normal SJR, the player has to frame perfectly time their aerial so that they land the exact frame after the animation ends in order to get the animation transition frame. With Quick Attack however, the player can touch the ground at any point during Quick Attack's dash to get the animation transition frame, which along with how Quick Attack functions, makes it far easier and much more versatile and practical than a normal SJR.
While the technique itself is not highly difficult as the player simply needs to Quick Attack into the ground and they have a 10 frame window to buffer whatever option they want to cancel with, it is a very difficult technique to master due to its high mixup potential and its tough execution to perform multiple times in succession. When mastered however, the technique is incredibly useful.
The technique is considered vital for competitive Pikachu players, due to its high versatility. It gives Pikachu a way to quickly maneuver around the stage without much lag, massively helping Pikachu's approach and aerial game, as well as giving it a getaway option. It can also easily play "mindgames" with the opponent due to the move's high mixup potential, easily allowing it to bait and punish opponents. It can also allow extended followups to certain moves knocking the opponent across the stage. Notably, it is an efficient way to lead into a neutral aerial, which is one of Pikachu's move effective KO moves due to its low startup and decent power.
The technique also makes Quick Attack highly effective as a locking tool. As Quick Attack has a 0 degree angle and it has low knockback, it can lock opponents very effectively and when combined with Quick Attack Canceling, this can allow Pikachu to potentially infinite the floored opponent if the Pikachu player has the execution. The move is not a true infinite as the Quick Attack's knockback does scale but it can lead into 0-death combos. Pikachu can even set up a QAC lock using up aerial into footstool, making it practical to go for in matches. Even if the player does not continuously Quick Attack the opponent, they can still get a guaranteed followup as the floored opponent gets up.
The technique also has utility on slopes as if Pikachu QACs on a slope, Pikachu will stay in the air for longer and gain additional momentum as it lands. This is naturally very situational however, especially in a competitive setting. In Smash 4, slopes enable Pikachu to QAC (even on the tiniest inclines such as on Dream Land in certain positions) which it normally cannot do, allowing Pikachu to greatly take advantage of slopes in Smash 4.
The technique is overall a great addition to Pikachu's kit as it gives a move which is already an excellent recovery and a solid approach option with strong mixup potential even more utility, improving it in the areas where it is already strong as well as making it safer and more versatile.
Quick Attack Edge Canceling
While Pikachu can only perform Quick Attack Canceling in Brawl and in Smash 4 on slopes, Pikachu does have another technique to cancel Quick Attack which works in every game prior to Super Smash Bros. Ultimate. If Pikachu spaces and angles Quick Attack in a certain way near a ledge, Pikachu can edge cancel the move as the dash ends. In Smash 64 and Melee, the Quick Attack requires very tight spacing in order to edge cancel but the spacing is more lenient in Brawl and Smash 4.
Due to its difficulty, the technique is not commonly utilised in Smash 64 and Melee although the technique is still naturally useful. The Break the Targets (in both games) and Board the Platforms world records see Pikachu utilising Quick Attack edge canceling on at least one occasion.
In Brawl and Smash 4, the technique is more versatile and useful, especially in the latter due to the lack of standard QAC on flat surfaces. The technique can be used to aid Pikachu's platform game and it can also be used to quickly either grab the ledge or simply get off stage to set up an edgeguard.