Note: Not to be mistaken with Air Dashing.
Often called "Air Dodges", this is an evasive move which can be done in the air to get out of harm's way. These techniques come with invincibility or even intangibility for at least part of the animation. Games may demonstrate the length of this safety through the character flashing white as simply have the property last for the whole animation like Astro Boy: Omega Factor.
Astro Boy: Omega Factor is a rare case where multiple air dodges can be stringed into each other to avoid Bullet Hell scenarios, even cancelling each other up to a limit which can be levelled up as the player progresses.
Platform Fighting games in particular tend to have the mechanic as a defensive option to recover from off-stage and land more safely in general as blocking mid-air is very uncommon, however the implementation varies even amongst the subgenre.
Super Smash Bros. Melee (2001) introduced the concept with the player falling helplessly after being done but has minimal landing lag with air dodging being directional which allows for wavedashing for a range of positional options. This model has been adopted by numerous indie games within the genre like Slap City.
Super Smash Bros. Brawl (2008) retooled it to only carry inertia from prior movement and not cause helplessness till landing. 2014's Super Smash Bros. for Wii U/3DS has considerable landing lag when done close to the ground and carries over the air dodge from its predecessor otherwise.
Super Smash Bros. Ultimate fuses the system from prior games by a neutral air dodge input producing a Brawl/Smash Wii U aerial dodge while directional ones can be done if with the analog stick outside of the neutral position. The player can't become helpless but can't perform actions for a second mid-air after dodging. Wavelanding, a specific sub-technique of wavedashing, returns as of the E3 2018 build of the game but less effective than in Melee.
All Smash Bros games up to this point have the invincibility begin within a few frames (2-5) of starting the dodge and have the effect last for 15 to 27 frames making it unsafe defensive tool. Bayonetta differs from this as she has a mechanic called "Bat Within" which allows her to evade with more risk earlier in her evasive animations. This carries over from her game series as a purchasable skill.