Jigglypuff turns toward the screen and falls asleep for about 3 seconds. Unlike the sleep state caused by other moves, Jigglypuff cannot wake up faster via button mashing. Before Jigglypuff falls asleep, any opponent in contact with it is instantly hit, with a ping sound being heard (except in the Japanese version of Smash 64, where a heavy kick sounds plays). This attack is nearly infamously known for having high knockback, instant startup lag (as it hits on frame 1 in Smash 64 and Melee and on frame 2 in later games), very small range, and a long vulnerability period. Jigglypuff gains intangibility for about 25-30 frames (depending on the game) at the start of the move, approximately the time it takes to close its eyes; however, this is unlikely to protect the user in case of a miss due to the move's extreme ending lag.
In Super Smash Bros., Rest is a powerful move that deals high damage and strong horizontal knockback. The move deals 20% and it is capable of KOing most characters under 50% at the center of Dream Land. The move comes out instantly on frame 1 (although it is only active on this frame), has a reasonably sized hitbox and it provides 29 frames of intangibility during its startup. However, the entire move takes 249 frames (over 4 seconds) to complete, which leaves Jigglypuff vulnerable for an extremely long period of time. When used on or above the stage, Jigglypuff's opponents have a lot of time to punish Rest and when it is used off stage, it leads to a guaranteed self-destruct unless something hits Jigglypuff upwards before it reaches the bottom blast zone.
Because of its frame 1 startup and its powerful hitbox, Rest is an extremely effective combo ender. Jigglypuff has a multitude of ways to combo into Rest for a KO, such as with a forward throw, up tilt, up aerial or down aerial. These setups into rest reduce the move's otherwise extreme risk to use.
In the original Japanese version of Smash 64, Rest was much weaker, only dealing 14% damage and much lower knockback (especially at lower percents). The move did not KO nearly as early as in the international versions, making the reward for landing it much lower. The move also did not make its signature "ping" sound effect. Rest was the only move Jigglypuff had which received a major change in the international version, being the main reason why Jigglypuff is considered better in the North American version. In the PAL versions of the game, Rest's hitbox size was noticeably reduced, which made the move harder to land than in NTSC versions. This smaller hitbox would be carried over to Melee.
In Super Smash Bros. Melee, Rest's already extreme power was exponentially increased. The move now deals 28% damage and it is capable of KOing most characters under 15% from center stage (on tournament legal stages) and it can even OHKO in certain situations (depending on the opponent's stage position and DI). Rest can still be combo'd into using some of Jigglypuff's moves (albeit not as reliably as in the previous game), such as up throw or up aerial. Because of this, Rest is an even more devastating tool than in the previous game and it is one of Jigglypuff's main ways to score KOes.
A minor change the move received was that it now has a flame effect rather than a normal effect, with the move now setting opponents on fire when it connects. The only downsides Rest has compared to its Smash 64 incarnation is that it has a considerably smaller hitbox (being the slightest bit smaller than its hitbox in the PAL versions of Smash 64) and its intangibility lasts for 3 less frames. These changes however are minuscule compared to its greatly increased power, making Rest one of Melee Jigglypuff's most defining moves, being one of the main reasons why Jigglypuff is considered to be a top tier.
In Super Smash Bros. Brawl, Rest has seen some rather drastic changes, mostly for the worse. One positive change is that the move now has a flower effect, which enables the move to build up more damage after it connects (now being able to deal a maximum of 42%). Two more positive (albeit minor) changes are that the move has a slightly bigger hitbox and it has one more frame of intangibility.
One notable change is that the move now launches vertically. This makes the move much safer when it KOes opponents on the ground (as it will always cause a Star KO or Screen KO) and it can even still be somewhat safe when used off stage as it will still cause a Blast KO (granted that the opponent is not too close to the stage). However, this vertical angle also makes the move much less safe if it does not KO.
The move however has seen two negative changes. The first negative change is that the move now comes on frame 2 rather than frame 1, although this is rather insignificant overall. The second and far more detrimental change is that the move has drastically reduced damage (only dealing 15% without the flower effect, nearly half as much as in Melee) and knockback (with Rest no longer being able to KO reliably until around 75% or maybe at even higher percents). This makes Rest a much less useful move, being more of a high risk, low reward move than a high risk, high reward move. This change combined with the game's numerous universal changes have hindered Rest even further, as Jigglypuff has less reliable ways to set up into it. The only setups Jigglypuff really has are with down aerial and from a jab lock, with the former being unreliable and only working at very high percents, while the latter is extremely situational. As a result, Rest is a far less effective move than it was in Melee, being one of the main reasons why Jiggypuff became so much worse in Brawl.
Rest in Super Smash Bros. 4; had seen multiple changes which improved the move overall. The hitbox is larger and it now lasts for 3 frames rather than 1. In addition, the move now has 20 frames less ending lag (although the move is still incredibly punishable). The most beneficial change the move received however is that it now deals 20% damage, which grants it greater knockback. This means that Rest can now KO lighter characters at around 50%, although heavier characters can survive it for quite a bit longer. However, Jigglypuff still lacks reliable setups into Rest, especially with the changes to its down aerial, as well as with some other moves.
Additionally, there is now a chance that the move will cause a Blast KO on stage (due to universal changes), so even if the opponent is KOed, they can potentially now re-spawn and punish Jigglypuff, increasing the risk of using Rest even more, despite its decreased ending lag. Additionally, the move can now potentially cause a Star KO off stage, which will usually result in Jigglypuff getting KOed before its opponent. Overall, while Rest was repurposed to be a lower risk, higher reward move, various changes (both universal and to Jigglypuff) have somewhat caused an opposite effect in a way, although it is still functionally superior to its Brawl counterpart.
Rest in Super Smash Bros. Ultimate now triggers a special zoom when it connects. Besides that, the move has seen multiple improvements with the move receiving a larger hitbox again (although it is still smaller than in Smash 64) and the move has less ending lag (especially when Jigglypuff lands the Rest). This reduces the risk of using Rest although Jigglypuff's opponent can still punish it if it connects (granted that they get a Blast KO). Additionally, Jigglypuff has gained a few potential setups into the move; mainly with Pound and down aerial, due to their buffs. Overall, Rest in Ultimate is improved compared to the previous two games although it still pales in comparison to its Melee counterpart.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Rest is a Psychic-type status move introduced in Generation I. Unlike it's counterpart in Super Smash Bros, rather than damaging opponents, it puts the user to sleep for two turns in exchange for recovering all of their HP back to maximum and healing any status ailments. The two turns of sleep may leave the user open to their opponent's attacks or setup, unless the user has an item or Ability that can cure the sleep early or the user knows Sleep Talk.
In the Super Smash Bros. series, Rest also puts the user to sleep and leaves it vulnerable in exchange for a powerful effect, but instead of healing damage, it deals damage with very powerful knockback if used right next to a foe. In the description of one of its Melee Smash trophies, as well as in Snake's Codec Conversation about Jigglypuff, it is stated that this is because at the instant Jigglypuff falls asleep, a huge buildup of energy forms at the center of its body. This is an example of the Smash producers changing the functions of a move to suit the games; other examples of this from the Pokémon series include Withdraw and Double Team.
In every Pokémon generation, Jigglypuff can learn Rest by leveling up, being one of the few Pokémon that can do so. Also, nearly every Pokémon can learn Rest via TM44.