𝚚𝚞𝚒𝚛𝚔 𝚒𝚍𝚎𝚊𝚜 ☞ 𝚋𝚗𝚑𝚊 (Editing!)

The Quirk Types

Emitter 
have the ability to either release certain substances, or alter materials around them in certain ways. Emitter-type Quirks usually require a conscious effort to activate (such as Electrification, Explosion, and Half-Cold Half-Hot), and some even require large amounts of concentration in order for them to remain active (such as Erasure).

Emitter-type Quirks can also have various ranges. While some users require physical contact to use them (such as Zero Gravity) others can have much longer ranges with no distance restrictions (such as Navel Laser). While most Emitter-type Quirks users generally have a handle on their own "emissions", it's also possible for users to hurt themselves from coming into too much contact with their Quirk (Explosion). In the case of generating substances, making too much too fast or for too long can harm the user as they are using reserves from their own body (Creation), or gradually lose their natural resistance to their own harmful Quirk (Acid). The emissions of Emitter-type Quirks can have a wide variety of properties and abilities.

While some substances produced by Emitter-type Quirks have common properties (Cement), some are unique to the user, and thus have special properties. Those who alter the properties of materials around them can also widely vary in effects, from molecular alteration (Softening) to molecular destruction (Decay). Emitter-type Quirks are, by a wide margin, the most common type of Quirk.

Transformation
cause the user to take on a temporary alteration of some kind. Transformation-type Quirks allow the user to temporarily "transform" their body in a variety of manners, sometimes enhancing existing features (Hardening, Gigantification) or perhaps adding new features to the body altogether (Tool Arms). Transformation-type Quirks generally affect the user exclusively, the only known exceptions being the Meatball Quirk.

Transformation-type Quirks usually require a close-range proximity in order to fully utilize them in combat due to them only affecting the user's body. Transformation-type Quirks are also the only known type of Quirk that can bestow the user attributes they do not normally exhibit by default. Transformation-type Quirks usually require a conscious effort by the user to "activate", though most users can be trained to initiate them reflexively (depending on the conditions required for activation) and practice to initiate their Quirks with greater intent and precision (such as with Edge Shot and his Foldabody Quirk, which he's mastered to change in any way in an instant). While Transformation-type Quirks are often quite powerful, their biggest weakness is that their effects are often temporary, and over-exertion usually leads to negative repercussions on the user's behalf. Transformation Quirks can also be limited based on the user, how resilient their body is, and the resources they have available to them (Tetsutetsu Tetsutetsu describes that his Steel Quirk softens if he doesn't consume enough Iron, and suffers from Iron Fatigue if he maintains the Quirk too long). Some users even condition their body in certain ways so that their Quirks can operate more effectively.

Because this type of Quirk combines the activation time and mutant-shape aspects of the other Quirk types, it is also often known as Hybrid or Composite. Transformation Quirks seem to be the least common type of Quirk.

Mutant
can have a wide variety of features and abilities depending on the individual. Generally, Mutant-type Quirks are associated with the user's physicality (mutations). As a result, Mutant Quirks are passively active and, at a glance, are the most identifiable.

Mutant-type Quirks create bodily structures that bestow the user more complex abilities that Emitter and Transformation Quirks cannot safely provide. Often times they will bestow prehensile appendages that allow for greater degrees of control (Vines) or structures added to pre-existing limbs to enhance pre-existing abilities (Engine). Mutant-type Quirks even have the ability to channel certain aspects of their user through them similarly to Emitter-type Quirks (Earphone Jack).

While not necessarily a weakness, Mutant-type Quirks cannot be turned off, and sometimes cause the user inconvenience due to their malformations. Such is the case with Mashirao Ojiro and his Tail Quirk, (which makes it difficult for him to sit or lay down) as well as Toru Hagakure and her Invisibility Quirk, (which makes it impossible to see her reflection or show up in photographs). Though because these Quirks are passively-active, they are partially immune to Quirk-disabling effects such as that of Shota Aizawa's Erasure Quirk.

Mutant-type Quirks are also the only known type of Quirk which can be passed down through generations without necessarily bestowing the corresponding ability (such as with Fumikage Tokoyami and his bird-like head that has nothing to do with his Dark Shadow Quirk, or Koji Koda's malformed head (from his mother's side, apparently) which speaks nothing to his Anivoice Quirk. As a result of this, while it's uncertain how common mutant Quirks are, it can be safely assumed they are the most commonly inherited.

Accumulation
Technically, Accumulation-type Quirk is not a particular category by its own like the previous three but a condition. Some Quirks as One For All, Rewind, and Fat Absorption have to accumulate power, energy, mass or a particular resource as a prerequisite condition to function correctly.