Priority

Priority is a property of hitboxes in the Super Smash Bros. series that describes their behavior when interacting with other hitboxes. While the priority of the hitboxes produced by normal ground attacks follows a set of rules that is dependent upon the amount of damage they deal, different rules apply to those of normal aerial attacks, certain special attacks when performed in the air. Furthermore, some hitboxes and attacks possess a special kind of priority called transcendent priority, which ignores the rules of normal priority. It should be noted that priority applies to individual hitboxes within attacks, as opposed to whole attacks. For example, the rules of normal priority apply to all the hitboxes of Lucario's f-smash, except that of its sweet spot, which has transcendent priority.

Ground attacks
The hitboxes of ground attacks interact with each other in terms of the damage they deal. When two ground attack hitboxes collide, they will either cancel each other out, or one will override (out-prioritise) the other. This collision is signified by a white "bubble", and in Melee, a clanging sound, as if swords are crashing, is also heard. For one ground attack to out-prioritise another, it must deal over 8% damage more than the other attack. In this case, the weaker hitbox is cancelled by the stronger one. However, if two colliding ground attack hitboxes deal within 8% of each other, they will "clash", and both will cancel out, delivering no damage to either character.

For example:
 * In Brawl, if Marth's un-tipped f-smash collides with Ike's f-smash (14% vs. 22%), they will clash and cancel each other out.
 * However, if Marth's un-tipped f-smash collides with Ganondorf's f-smash (14% vs. 24%), Ganondorf's f-smash will cancel out (out-prioritise) Marth's f-smash.
 * If Captain Falcon's f-smash collides with Ness' u-tilt, Captain Falcon's f-smash will out-prioritise Ness' u-tilt (19% vs. 7%).

The same rules apply when ground attack hitboxes are matched against regular projectile hitboxes.

For example:
 * Marth's un-tipped f-smash is out-prioritised by Samus' fully charged Charge Shot (14% vs. 25%).
 * However, if the second hitbox of Bowser's f-smash collides with Samus's fully charged Charge Shot, they will cancel each other out (23% vs. 25%).

Aerial attacks
Priority works differently for aerial attacks. When it comes to ground attacks vs. aerial attacks or aerial attacks vs. aerial attacks, the rule of priority doesn't apply. As such, it is impossible for the hitboxes of standard aerial attacks to collide with the hitboxes of ground attacks or other standard aerial attacks. However, the hitboxes of aerial attacks can collide with projectiles. The law of priority works the same way, except aerial attacks cannot be canceled out. So if Marth's fair collides with Samus's fully charged Charge Shot (10% vs. 25%), Marth's fair will not be canceled out but Marth's fair will fail to cancel out Samus's Charge Shot. As a result, the collision action will occur, but Samus's Charge Shot will go through Marth's fair and hit him. But if Ganondorf's fair collides with Samus's Charge Shot (17% vs. 25%), Ganondorf's fair will cancel out Samus's Charge Shot and Ganondorf will be unharmed.

Airborne special moves
While standard aerial attacks do not follow the law of priority, some special moves when airborne and Meta Knight's glide attack can collide with the hitboxes of ground and standard hitboxes. Just like when it comes to standard aerials vs. projectiles, these attacks cannot be canceled out since they're airborne. When the hitboxes of these attacks collide with the hitboxes of ground attacks, they follow the same priority range. If the hitbox of the ground attack is below the priority range, what normally happens will occur. If the two hitboxes are within the priority range, the ground attack will be canceled out but the wielder of the ground attack will be completely unharmed. For example, if King's Dedede u-tilt collides with Meta Knight's glide attack (12% vs. 13%), Dedede's u-tilt will be canceled out, but he'll be unharmed, even if the hitbox of Meta Knight's glide attack connects with King Dedede. If the hitbox of the ground attack is above the priority range, neither attack will be canceled out and if the hitbox of the ground attack connects with the character using the airborne special, they will take the damage and knockback of the ground attack.

An example of a special move that can collide with the hitboxes of other attacks while airborne is Meta Knight's Mach Tornado. While grounded, it can be canceled out. If airborne, it cannot be canceled. If Captain Falcon's f-tilt collides with an hitbox of Meta Knight's Mach Tornado while grounded, Captain falcon's f-tilt will cancel out the Mach Tornado (10% vs. 1%). If the Mach Tornado is airborne however, the Mach Tornado will not be canceled out but neither will Captain Falcon's f-tilt. So unless the hitbox of Captain Falcon's f-tilt connects with Meta Knight, the Mach Tornado will continue and still possibly damage Captain Falcon, even though his f-tilt "outprioritized" the Mach Tornado.

Transcending priority
In Smash Brothers, some hitboxes have what is known as transcending priority (also known as transcendent priority). These hitboxes do not have priority and thus are incapable of colliding with other attacks. As a result, these hitboxes are completely incapable of canceling out opposing attacks. However, attacks with these hitboxes are also completely incapable of being canceled out by opposing attacks. For example, if two Meta Knights use their forward smash at the same exact time while within the range of each other, an attack with an hitbox that has transcending priority, the two forward smashes will not collide and continue to go through their full duration. If the two Meta Knights are close enough, both will be hit by each other's forward smash.

List of attacks with transcending priority
Here is a list of the attacks that contain hitboxes with transcending priority in Brawl. Note that even though there are standard aerials that have transcending priority, this only comes into play if they collide with an projectile, certain airborne specials, or Meta Knight's glide attack since the hitboxes of standard aerials cannot collide with the hitboxes of standard ground attacks and other standard aerials.


 * Charizard - U-smash
 * Falco - Blaster, Reflector
 * Fox - Blaster
 * Ganondorf - Dair
 * Ice Climbers - Squall Hammer, Blizzard
 * Ike - U-smash, d-smash, all aerials, Eruption, Aether (only the hitboxes after the initial hitbox)
 * Ivysaur - Neutral attack, Bullet Seed
 * King Dedede - All smashes, nair, Jet Hammer, Waddle Dee Toss (with Gordo only), Super Dedede Jump
 * Kirby - Dash attack, Hammer (both grounded and airborne versions), Final Cutter (both the sword strike and projectile)
 * Link - Spin Attack (both grounded and airborne versions)
 * Lucario - F-smash (sweetspot only), Force Palm (the projectile)
 * Lucas - F-smash, d-smash, nair, bair (sweetspot only), PK Freeze, PSI Magnet
 * Mario - F-smash (sweetspot only), Cape
 * Marth - Shield Breaker, Dancing Blade, Dolphin Slash
 * Meta Knight - Dimensional Cape, Shuttle Loop, all standard attacks except dash attack
 * Mr. Game & Watch - Chef (the frying pan and not the projectiles)
 * Ness - Dash attack, PK Flash
 * Olimar - D-smash (sweetspot only)
 * Pikachu - Neutral attack, f-smash (sweetspot only), d-smash, Thunder
 * R.O.B. - Robo Beam, Arm Rotor
 * Sheik - Needle Storm, Chain, Vanish
 * Snake - F-smash
 * Squirtle - U-smash
 * Sonic - Nair
 * Toon Link - Spin Attack
 * Wario - Wario Waft
 * Wolf - Blaster
 * Zelda - Neutral attack, f-tilt, u-tilt, dash attack, F-smash, U-smash (all but the final hitbox), nair, uair, Nayru's Love, Farore's Wind
 * Zero Suit samus - Dash attack, d-smash