Dash attack canceled up smash
The dash attack canceled up smash (abbreviated to DACUS, also referred to as Boost Smashing) is an advanced technique in Super Smash Bros. Brawl. It is similar to the slide smash, but more difficult to pull off and has the potential to be much longer. As its name implies, it is performed by initiating a dash attack with the C-Stick (or D-Pad if the player is using the Nunchuk; this is much easier when the C-Stick or D-Pad is angled downwards) and immediately afterward canceling the dash attack with an up smash command. Any character can do it, but only certain characters gain a noteworthy addition to their attack strategies because of it. The furthest DACUS requires precise timing and is timed differently for each character. The up-smash can also be replaced with a grab to perform a Boost grab.
Performing a non-sliding DACUS was briefly possible in early updates of Super Smash Bros. for Nintendo 3DS, prior to patch 1.0.4. It is no longer possible in any later updates of the 3DS version nor at any time in the Wii U version, although Shulk is able to perform a similar technique named MonaDACUS by using the momentum of a canceled Speed Monado Art to boost himself forward.
Uses of the DACUS are somewhat analogous to those of wavesmashing from the previous game. A DACUS is useful when the character physics behind it allow the up-smash to slide significantly far and fast across the stage while charging. It adds an extra factor to a character's KO potential, or can simply be used to surprise a distant opponent in the interest of maintaining close quarters. With good timing, it is possible for both the initial hit of the dash attack and the up-smash to connect, providing extra damage.
The Gatling Combo is similar to the DACUS, but the dash attack is cancelled after the hitbox comes out, meaning that both the dash attack and the up smash have the potential to hit. It only gains distance similar to that of a slide smash, with the exception of Snake's. The Gatling Combo is performed by inputting the up smash with a longer delay than for the DACUS. The combo is usually used to rack up some early-percent damage, and sometimes used against shielding opponents, as the opponent may drop their shield after the dash attack and then get hit by the up smash. However, at higher percentages, the opponent will be knocked away too far by the dash attack for the up smash to be able to connect properly. Falco, Snake, and Wario are currently known to be able to perform the Gatling Combo; however, Snake's slides too far for both the dash attack and the up smash to reliably hit when Snake doesn't slide into an edge, and Wario's Gatling Combo will only fully connect at low percents due to the up smash's poor range.
This is a short list of characters that have a sliding DACUS:
In the 1.0.0 to 1.0.3 versions of Super Smash Bros. for Nintendo 3DS, while all characters could DACUS, no character could perform a sliding DACUS. As of version 1.0.4, no characters can DACUS at all. This also applies to Super Smash Bros. for Wii U, as the two games are meant to share the same core mechanics.
Buffered dash attack canceled up smash
The buffered dash attack canceled up smash (shortened to BDACUS) is another variant of DACUS that has different inputs and input times. A BDACUS will result in a normal DACUS, but it will slide slightly further and has to be inputted during the ending lag of another move. Every character can use this technique but only characters that have an effective DACUS will get some usefulness out of it. It requires a player to use a move that will end on the ground and have the normal ending lag of 10 frames or use a spot dodge. In this small amount of time, the control stick has to be tapped forward then returned to its neutral state followed by two upward taps on the C-Stick. A BDACUS has no frames for the dash attack and will instead only come out as an up smash with great momentum.
Super glide tossing
In Brawl and Smash 4, the inputs for a DACUS can be used for some characters to super glide toss with items, and in most cases where a character can do a super glide toss and/or a jump cancel throw, a super glide toss will travel more distance, though it is trumped by regular glide tosses in Brawl if the character in question can perform it. It is also somewhat limited by how it works; when performed correctly, the dash item throw is cancelled with another item throw input (which must be inputted upwards, hence the DACUS input), resulting in an upward item throw that slides the character forward. Regardless of its limitations, the technique is most useful with Link; while he gains merely average distance with a super glide toss, he can generate Bombs to use it immediately (while most other special moves that generate items take a considerably longer time), and he cannot glide toss using the regular method and gains less distance with jump cancel throws. He is also one of the only characters in both games that can additionally super glide toss an item forward (should the cancel be delayed) while retaining a decent distance; the result is Link throwing an item forward while sliding forward, then waving his arm upwards as if he is throwing another item. This has the effect of shortening the dash item throw animation.
Super glide tossing can also be performed with a dash throw inputted with Z and hitting the C-Stick upwards (while both are set to their default action), which enables some characters (like Mega Man) to slide even farther than the DACUS input would allow.
In Smash 4
Characters that can super glide toss forward
*Does not actually gain distance regardless of cancel timing, but still shortens his dash throw animation with an upward throw if it is delayed.
Characters that can only super glide toss upward