A rolling dodge, or simply roll (called EscapeF and EscapeB internally in Melee's debug menu and Brawl's files, depending on which direction the character is rolling) is a maneuver that moves the character left or right and allows them to dodge attacks for a short period of time. It is performed by pressing the Control Stick left or right while holding a shield button.
Characters experience intangibility frames while rolling, though the amount, duration and timing of these frames varies from character to character. It's an advantage to have quick and long rolls because if it's slow and short, the roll is more predictable and the character is generally more vulnerable to attacks. Most characters use a rolling, somersaulting or spinning animation for this technique, hence the name, though others without a very acrobatic physique (such as Zelda or Mewtwo) will instead step back, slide or even teleport (the latter being the case for Palutena and Rosalina) into the direction the Control Stick is flicked, while others such as Kirby and Mr. Game & Watch use a cartwheeling animation. Yoshi and Samus use unique special animations for it: Yoshi rolls while in his Egg, and Samus goes into Morph Ball mode, though both rolls are considerably slow.
After rolling, characters will always end up facing the opposite direction they rolled into. That is, characters that roll backwards will remain facing the same way, while characters that roll forwards will turn around. This allows rolling through a character to then execute attacks with more ease, but can disrupt them when trying to dodge and approach the opponent at the same time. Additionally, characters cannot roll off edges; they will instead perform the remainder of their rolling animation while staying in place at the edge.
Computer players often use rolls to evade attacks, especially at high levels. Due to the rolls' unique trait of moving the character while dodging attacks, most casual players tend to overrely on them attempting to keep themselves safe from attacks, even using them over their regular shields. In reality, due to its noticeable duration and vulnerability frames near the end, excessive rolling can leave the user more vulnerable against attacks, as the opponent can read their reaction and throw an attack into the direction they are going to roll into to punish them, or use attacks that hit at both sides and/or have long-lasting hitboxes, such as down smashes and neutral aerials. Additionally, simply faking a rush can threaten and condition such a player into rolling, allowing the rusher to punish them.
In Super Smash Bros. Ultimate, rolling repeatedly causes each subsequent roll to be executed slower (thus increasing its lag) and grant less intangibility frames, leaving the player far more open to punishment should they fail to use the technique sparingly. This trait also applies to spot dodges, in a way so overusing either dodge also affects the others.
Rolling vs. wavedashing (Super Smash Bros. Melee)
Many casual players believe that rolling and wavedashing play the same role and that the wavedash is just a superior version of the roll. This misconception exists because professional players wavedash in most situations in which casual players would roll. In fact, rolling and wavedashing play very different roles: rolling provides intangibility and generally more distance than a wavedash, but has a determined length and is more easily punished; it is generally used to get behind an attacking opponent or avoid attacks that cannot be wavedashed away from. On the other hand, wavedashing allows a character to act faster and attack while moving sideways at the expense of intangibility; it is generally used to quickly alter spacing or move towards an opponent while standing without turning around (like a forward roll would cause). If the wavedash did not exist, upper-level smashers would replace the wavedash with a dash dance in most situations, not a roll.
Rolling frames in Smash 64
All rolls have 3 vulnerable frames as soon as they start, then they're invulnerable until frame 19 (except for Samus, who is invulnerable until frame 23).
Rolling frames in Melee
These lists show the intangibility and the total lag frames of the rolls, but not the distance travelled or the size of the character while rolling.
Rolling distances in Melee
Average of forward and back rolls
Rolling frames in Brawl
Rolling frames in Smash 4
In Smash 4, rolls have been sped up slightly for the majority of the cast, making them safer for repositioning and getting away from attacks. Additionally, with the exception of Greninja, all characters have identical frame data between their forward and back roll.
Rolls have been slightly nerfed in updates, with both version 1.1.0 and 1.1.1 reducing their intangibility by one frame at the end. The following list shows the frame data of rolls as of the latest version of the game.
Rolling distances in Smash 4
Average of forward and back rolls
Rolling frames in Ultimate
In Ultimate, the effectiveness of rolls has been reduced overall. While forward rolls keep the same overall speed as in Smash 4, back rolls have received more ending lag by five frames on average, and grant intangibility one frame later for most characters. As a result, back rolls are now different from forward rolls for every character, unlike in previous installments, and due to their higher lag, rolling away from opponents is generally more punishable. Both types of rolls also grant slightly less intangibility across the cast, though this is compensated for some characters with slightly reduced ending lag on their forward rolls. Most notably, the rolls of Bayonetta, Samus and Yoshi, which were the slowest in Smash 4, have been sped up relative to other characters.
In addition to the direct changes to characters' rolls, a staleness mechanic has been introduced, which reduces their intangibility frames and lengthens their duration if they are performed repeatedly, gradually leaving the user more vulnerable. This mechanic is shared with spot dodges and air dodges.
The formula to determine a roll's duration before it can be interrupted is D * (1 + P), where D is the total duration of the roll when fresh, and P is a penalty value that increases by 0.06 for every forward roll, and 0.1 for every back roll. The penalty value caps at 0.3 for forward rolls, and 0.5 for back rolls; as a result, five consecutive uses of either roll will fully stale them, and back rolls have their duration increased more than forward rolls. The penalty is reset per each roll used every time the player spends roughly one second without using any kind of dodge. When fully stale, all rolls grant intangibility four frames later, making them worse for escaping pressure.