Priority

Priority is a property of hitboxes in the  games and in Super Smash Flash 2 which describes the behavior when they interact with each other. The priority of hitboxes produced by normal ground attacks follow a set of rules that are dependent upon the amount of damage they deal (the law of high and low priority). However, different rules apply to those of normal aerial attacks and certain special moves when they are performed in the air. Some hitboxes and attacks, such as shots from 's, possess transcendent priority, which ignore the rules of normal priority. There is no priority in the original Super Smash Flash as attacks hitboxes cannot collide and simply pass through each other, sometimes damaging one character or both of them.

Priority applies to individual hitboxes within attacks, not the attack as a whole. However, in the event that a single hitbox is "out-prioritized", it is possible for the whole attack to be cancelled.

There is no true priority in the original Super Smash Flash, attacks simply pass through themselves, in the case of projectiles, and character model, they do not cancel each other. In all cases, the deal out of attacks will be determinated by which input was triggered first.

Normal priority
Normal priority describes the set of rules that apply to normal attack hitboxes which means that any attack hitbox that is not classified as transcendent. The majority of neutral attacks, aerials, special attacks and projectiles contain hitboxes with normal priority.

Ground attacks and projectiles
The hitboxes of normal ground attacks are based on high and low priority; they interact with each other in terms of the damage they deal. When two ground attack hitboxes collide they will either cancel each other out (this is called a clank), or one will override (out-prioritize) the other. This collision is signified by a white "bubble" and a distinct "ting" sound.

If one attack hitbox is above the priority range of another then the stronger hitbox out-prioritizes the weaker one and the weaker attack is cancelled by the stronger one. However, if two colliding ground attack hitboxes are within the priority range, they will "clash", and both will cancel out with characters not receiving any damage at all.

Aerial attacks
Different rules apply to the hitboxes of normal aerial attacks. When a normal aerial attack hitbox overlaps that normal ground attack or another normal aerial, the attacks cannot collide or clash with each other and the "law of high and low priority" does not apply. However, if this occurs, both will persist, irrespective of each, and will damage opponents if the move connects; this is called trading. The hitboxes of aerial attacks can collide with normal projectiles; in this case, high and low priority functions. However, aerial attack animations cannot be canceled out, and will continue even if out-prioritized.

Extending hitboxes
As stated above, when an attack overrides or out-prioritizes another move, sometimes the attack that out-prioritizes the other attack ends having their hitbox extended or keep the hitbox active. For instance if Wario uses his forward tilt on 's Ki Blasts, Wario's tilt will out-prioritize the Ki Blasts and he will move forward a bit. Something similar happens when 's and 's forward smashes collide. Marth's forward smash will out-prioritize Lloyd's forward smash and end up with Lloyd being hit by the Sweet spot of Marth's blade.

Transcendent priority
Transcendent priority describes the set of rules that apply to transcendent attack hitboxes, as distinct from normal attack hitboxes. Transcendent hitboxes ignore the rules of normal priority: they cannot collide with, clash with, cancel out, or be canceled out by other hitboxes.

Below is a list of character's attacks that contain hitboxes with transcendent priority.


 * — Kamehameha
 * — Hammer (both grounded and aerial)
 * — Cape, Mario Tornado (the Luma), forward smash (sweet spot only).
 * Mega Man — Mega Buster (stage 1/uncharged), Water Wave, Crash Bomber, up aerial.
 * — Dimensional Cape, up, and down throws.
 * — Up tilt
 * — down smash, forward smash (sweet spot only).
 * — Wario Waft.
 * —, forward tilt, up tilt, dash attack, forward and up smashes, and neutral and up aerials.
 * Certain Final Smashes.
 * —, forward tilt, up tilt, dash attack, forward and up smashes, and neutral and up aerials.
 * Certain Final Smashes.

Trivia

 * In older demos, a fully charged Kuroi Getsuga could be outprioritized by a regular Getsuga Tenshō.