A Kirbycide is a technique specific to Kirby in which Kirby immobilizes an opponent and forces the victim to self-destruct. The name was coined by t1mmy and was popularized by the YouTube video 1-800-KIRBYCIDE.
Kirby can SD from a Kirbycide, though a "SD-cancel" (see SD-canceling, below) can be used in order to survive. Although there are various ways for Kirby to KO himself while SDing, the following are considered the only true Kirbycides:
This is perhaps the best-known Kirbycide. It has been nicknamed Swallowcide and has been around since the original Super Smash Bros.. To execute this move, Kirby has to trap an opponent in his mouth using his neutral special move, Inhale, and walk off the side of the stage. What makes this form of Kirbycide so effective is that the amount of time required to break out of the Swallow is not affected by the opponent's damage, so it can be performed as low as 0%. Additionally, once Kirby is plummeting off the stage, any opponent who breaks free will drop downward while Kirby stays overhead with all jumps. Also, Kirby never SD's before his opponent off-screen allowing him a fraction of a second to jump and thereby recover back to the stage. King Dedede can use his version of Inhale to use this version of Kirbycide (jokingly called "Dededecide"). Another form of this attack is jumping off a high ledge and falling towards a side of the screen, then spitting an opponent out of the boundary lines.
The effectiveness is reduced even further in Super Smash Bros. 4, as Kirby gets KO'd first, meaning Kirby will lose instead of winning or tying if he performs it when him and his opponent are on their last stocks, though certain characters when Swallowcided with may instead cause Sudden Death. The opponent is additionally released, allowing them to potentially recover back to the stage.
After grabbing, Kirby can force his victim into a SD by using a back throw at the edge of the stage. The opponent has a chance to break out of the hold even after the throw is executed, the amount of time required is affected by the victim's percentage, and can be broken out of quickly at low damage. The timing of Kirby's SD varies from character to character (and stage to stage), but Kirby often SDs after his opponent allowing this Kirbycide to be used to win a match. In Brawl, Kirby will not leave the stage when using this on the edge, getting rid of this form of Kirbyciding. Even if performed on a quickly moving platform (e.g. the large moving platforms once Frigate Orpheon flips), the move appears to have a timer and once it runs out, the move will end, even in mid-air.
The method of Kirbyciding with the forward throw is the same as the back throw; grab an opponent who is near the edge of the stage and leap over the side. The forward throw is much harder to pull off compared to the back throw because the throwing animation is longer, giving the opponent more time to break free. Kirby often SDs before the opponent with this Kirbycide. Again in Brawl, this method was disabled due to moving off the edge of a platform being disabled. Again, the move seems to have a timer.
Up throw (Forward in Smash 64)
Using the up throw to cause the opponent to SD requires Kirby to be at the very end of a ledge when he grabs. If the conditions are correct (that of stage chosen and victim's character) Kirby will leap up as usual, but miss the stage on his way back down resulting in both players SDing off the bottom. This Kirbycide is unique in the fact that the opponent cannot break free. However: Kirby will SD before the opponent, which ends the Kirbycide and gives the opponent a scant few frames to SD-Cancel. In Melee and Brawl, this is not as detrimental as it seems because - aside from the strict timing requirement - many characters are incapable of recovering from the very bottom of deep stages, and some stages have hazardous environments - such as Jungle Japes' rushing water and lurking Klaptrap. However, in Smash 64, the opponent will always be released just before being KO'd (while Kirby will always SD), and on stages like Dream Land, it is even possible for characters like another Kirby, Pikachu, and Luigi to recover. If used near the beginning of Rainbow Cruise or any time on Icicle Mountain, Kirby will hit one of the platforms above, causing both to die. There is also a glitch in Icicle Mountain that if the up throw is performed under a destructible ice block and there are only pass-through platforms underneath, Kirby will stop going up at the ice block, and fall through all the platforms underneath and cause both players to die. In Brawl, the usual Up throw Kirbycide cannot be performed because of a stopper that seems to halt Kirby's dive a certain distance after rising up. The falling distance is fixed after the rise, so Kirby can fall a great distance off a ledge before actually finishing the move if he is stopped by a ceiling while rising up. This means the Up throw Kirbycide can still be used on stages with some sort of ceiling over a ledge, such as the lower center platform of Skyworld and the lower area of New Pork City. It can also be used on the lower-right area of Temple. The Kirbycide is almost the same as the original Super Smash Bros. and Super Smash Bros. Melee, but the opponent dies at the same time of Kirby, preventing any SD-Canceling. Also, the up throw Kirbycide for Rainbow Cruise still exists in Super Smash Bros. Brawl. When using any type of these Kirbycides in Brawl, Sudden Death will occur. When an Up throw Kirbycide is used during a Sudden Death, the player with the greater controller priority in Brawl (P4 > P3 > P2 > P1) wins. Kirby's up throw can also be used to force both fighters into a hazard above them.
Final Cutter is a weak meteor smash, but it can KO Kirby as well if Kirby is too far away from a ledge, this technique has been nicknamed Cuttercide/Kutterkaze.
In Smash 64, Kirby always wins.
After Melee, it was made more difficult to win due to a higher threshold for sufficient knockback.
Chomp, Blunderbuss, and Inhale are moves which can be copied from Wario, King K. Rool, and King Dedede. These moves can function as sacrificial KO's when used by their native characters as well as when copied by Kirby, and are thus functional as Kirbycides.
A form of Kirbycide introduced in Brawl performable only on Big Blue. In order to perform, Kirby must break a Smash Ball, jump on the moving track way, then start the Final Smash. If a foe is sucked into the pot, then the opponent and Kirby will be carried off stage. Due to Big Blue and Smash Balls being Banned, this form of Kirbycide is never seen in competitive play.
When using a Swallowcide in Melee, Kirby will SD a fraction of a second after his opponent. In Smash 64, Smash 4 and Smash Ultimate, Kirby will SD before the opponent; and in Brawl, both Kirby and the opponent will SD at the same time (causing a Sudden Death when both characters are on their last stock). If the opponent has no additional lives, Kirby will survive without losing a stock. If the opponent does have a stock in reserve, Kirby must immediately recover back to the stage by jumping, or he too will SD. Another method is pressing upwards on the directional pad when the enemy is too low to recover, and then float up to safety.
The timing is rather precise, and varies with the size of the opponent - from zero to seven frames with the larger characters SDing sooner. "Zero-framers" are characters that SD approximately the same time as Kirby. This results in both characters losing a stock at approximately the same time which will lead to a Sudden Death on the last stock. If a Swallowcide is performed again (during the Sudden Death) Kirby and the zero-framer will both SD at approximately the same time again and the winner is determined by Melee's controller slot priority (P1 > P2 > P3 > P4).
This is due to the character's hurtbox remaining outside of Kirby's mouth (although invulnerable), and blast lines ignore invulnerability.
Below is the amount of frames that Kirby has to avoid his SD for each character in Melee, provided by Omnigamer.
It's worth nothing that King Kirby 90 has SD-canceled vs. Kirby in training mode (PAL) and t1mmy has SD-canceled vs. Jigglypuff in an actual fight (NTSC), providing proof that SD-cancels are possible even with no frames available to jump. Such a situation is most likely dependent on the distance between Kirby and the blast line the frame before the zero-framer dies. If he is far away enough from the blast line, Kirby will survive.
Strategy against Kirbycide
This is a very effective technique that usually ends in at least one players losing a stock. Staying away from an inhaling Kirby and using projectiles is the best way to avoid it altogether. If caught, the best thing to do is to not struggle and button mash after going off the stage. Doing so during a Swallowcide often makes the victim pop out below Kirby, resulting in a death while Kirby can simply float back onto the stage.
If the player is Kirby, it may or may not be wise to finish off by Swallowing the opposing character. If the player is down low enough and if the opposing character has bad vertical recovery, Kirby may survive with his immense recovery.