This kinda relates to my last post about quirks being passed down so here we go. I'm gonna lay out the basics and then explain what I'm trying to get at
There are three Quirk types in the anime being...
Emitter types: They release substances or change materials, and require some form of concentration may it be a little bit or a lot and are the most common type of quirk found in the BNHA universe. Some examples are
Navel Laser-Yuga Aoyama
Mutant types: They are exactly what they say they are, quirks that are apart of the user's body, and are not typical of the pre-quirk era physicality. They are also constantly on, and often have more complicated abilities than Emitter or transformation types. Some characters with a Mutant quirk are
Transformation: They cause the quirk user to temporarily change something, be it themselves, some part of themselves, or another person, though the only known quirk to alter another person is the Meatball quirk. Transformation quirks appear to be the least common quirk type. Some quirk examples are
Bendy Fingers-David Shield
Big Fist-Itsuka Kendo
Now that that is out of the way I'm going to talk about how the types are weird. I mean that often you find that Emitter types could be classified as a Mutant quirk (of course not counting mutations that are passed down like the Midoriya's green hair or Mina's horns that have absolutely nothing to do with her quirk). One Example of this would be Yuga's, Navel Laser. Classified as an Emitter type it allows him to fire lasers from his navel. Though it is never specified I would think that his navel would be altered so it could accommodate the lasers coming out of his belly button. Another Quirk that would be an example of this is Uraraka's Zero Gravity. Her quirk is activated by touching all five of her fingers to the object or person. If you ever look at her fingertips you will see that they will are pink when using her quirk, along with the fact that (yes I know this is stretching and it could just be apart of her character design but...) Her hair seems to defy gravity, could be a mutation caused by her quirk. Lastly Bakugou's Explosion. Bakugou excretes sweat that is similar to nitroglycerin from his palms that he can ignite. First off, his body has to literally change to create sweat that is similar to nitroglycerin, you can't just do that, his body has to have a mutation to cause this. Secondly, how is he igniting it? Yet again his body would have to have some sort of mutation to ignite the nitroglycerin sweat.
Could this possibly be another category? I personally think so, but anyway. That's all I could think of for this, for now, I'll update it if I can think of more.