Up Air Attack (abbreviated as "u-air", "Up-Air", "AUA", and "up aerial') is an aerial attack that is performed in midair by pressing the A Button, and tilting the control stick upwards. It also gains a moderate boost in height if the character's attack is a backflip used just before the apex of the jump but the user loses their second jump. Its official term varies between titles, where it is known as a "Up Midair Attack" in Super Smash Bros. Melee, and a "Up Air Attack" in Brawl. Many up aerials are circle kicks, which have large range, good priority and very slightly disjointed hitboxes. They can also send the opponent in diverse directions. A lot of up aerials can be used for Juggling.
Pikachu: Flips and hits opponents with his tail. A popular combo move and gimping tool. 10%
Yoshi: Flips while using his tail to do damage. A combo end move with low range preventing it from starting up combos. Incredibly useful out of up tilts vs any heavy or medium character using DJC's. 15%
Samus: Does a spin kick upward. Considered overall the worst up air attack in the game. Not too useful outside of baiting overly aggressive opponents and reading it into a backward air attack. 10%
Donkey Kong: Slaps upward. Using platform cancels, this is DK's main combo move outside of wall combos. Combos into other up air attacks or up smash attacks. 12%
Link: Thrusts his sword up. Good combo move but with poor range. Nice knockback. 16%
Luigi: Does a flip kick. Part of Luigi's main KO combo. 12%
Mario: Similar to Luigi but less useful. The low damage hit of the move can also combo as well into backward air attack. 12%
Kirby: Spins rapidly. Kirby's overall worst aerial, a very different form of aerial as it does 2 hits if it isn't Z-cancelled and 1 hit if it is. 10%
Jigglypuff: Slaps upward. Part of Jigglypuff's basic combo of Up Throw, Up Smash Attack, Up Throw, Multiple Up Air Attacks into a Down Special. 16%
Fox: Flips then kicks. Has set low knockback with the first hit. Infinites if only the first hit hits. Second hit has great vertical knockback. 15% in total.
Captain Falcon: Does a flip kick. Incredible hitstun and one of the most fearsome moves in the game due to its versatile uses in both combos and edgeguarding. Back of the hit is a very powerful semi-spike. 16%
Ness: Headbutts upward. Good for juggling and DJCing. 15%
Dr. Mario: A flip kick upwards, which is good for juggling fast fallers. 10% damage
Mario: A flip kick upwards. Good move for juggling and comboing. 11% damage.
Luigi: A flip kick upwards. Similar to Mario's but doesn't offer the same juggling properties from the ground as Mario's.
Captain Falcon: A backflip in midair with his feet out. Knockback direction depends on what angle the move hits the foe, though strong nonetheless. Also good for juggling. 13% damage.
Bowser: A hit upward hard with his head. Very high knockback, but one of Bowser's slower moves. It is the most powerful Up Air Attack and one of the most powerful air attacks in the game. 9%-17%
Donkey Kong: A headbutt upward, good for juggling fast-fallers. Does 14% damage.
Samus: Brings her legs above her body and spins. Several hits, up to 10% damage.
Jigglypuff: Waves it's hand up in an arch. Not the best air K.O'er, though excellent for juggling. 11% damage.
Kirby: A flip in mid air, kicking upwards. Great knockback, possibly Kirby's best KO move.
Link: Stabs sword above him. Good for juggling or Star KO'ing at higher damages ~120%. Has some Sex Kick properties. 16% damage, ~14% in later hitboxes.
Young Link: Aims sword upwards. Not good for KOing, but better at juggling. 12% damage.
Fox: A flip kick with immense upward knockback and high speed.
Falco: A kick up with his tail extended afterward. A two-hit move, first hit does 6%, then 9%.
Ganondorf: A backflip in midair with his feet out. One of his most useful and fastest moves and when used backwards. allows him to knock-out his opponents at low damage due to the semi-spike.
Pichu: A tail swing. Weak, with low damage and it can't finish his foe. But for these reasons it can juggle and set up more air moves and grabs for fast fallers. If SHFFL'd, can Wavedash at the end of the move.
Link: Points his sword upwards. Diverse diagonal knockback.
Zelda: Pulsates an explosion out of her hand. Large, disjointed hitbox, will kill off the top of the stage at low percentages (50% upwards).
Sheik: Spins her body around, with her feet pointing upwards. Sex kick like properties.
Ganondorf: A very quick, powerful circle kick. Can semi-spike.
Toon Link: Identical to Link's, except a very slight diagonal range and much more knockback. Can KO much easier than Link's. Has unbelievable priority, going through even Marth's Dolphin Slash
Samus: Very much like Sheik's. However, the first hits suck the opponent in; only the last hit gives (large) knockback.
Zero Suit Samus: A flip kick. However, it makes a slashing sound when it connects.
Pit: Spins his bow upwards. Diverse horizontal knockback.
Ice Climbers: Point both hammers upwards. High knockback, disjointed hitbox.
R.O.B.: Waves his arms upwards. Multiple hits, diverse knockback.
Kirby: A powerful flip kick. Insane combo potential when combined with throws and Utilt.
Meta Knight: Slashes upwards at an incredible speed. It is the quickest up aerial in the game. Can be used in combination with multiple jumps for chaining, can easily rack up 30% damage or more. High stun. Down throw to up aerial to forward aerial is one of the few inescapable combos in Brawl; it cannot be airdodged, attacked through, or DI'd out of, even if the opponent DIs away (if they DI upward from the down throw then this combo is even easier to land)
King Dedede: Spins his hammer upwards. Multiple hits, diverse knockback.
Captain Olimar: Throws a Pikmin upwards. The Pikmin spins around. Multiple hits. Hardest to DI out of if the Pikmin is yellow. In fact, Olimar can be falling and this attack will still complete and keep hitting the opponent as long as the Pikmin is yellow.
Fox: Whips his leg and tail upwards. Is very fast and powerful.
Lucas: Similar to Ness' in animation, but with more range, less knockback, and does not go in a full circle.
Mr. Game & Watch: Blows upwards. Opponents not hit with the attack are pushed upwards an extremely high distance. Distinct, useful attack that can set up for further combos. Typical of Mr. Game & Watch, this move has a large disjointed hitbox.
Snake: A midair handstand. Similar properties to Charizard's, with higher knockback.