In the months since I first wrote this story, I've witnessed more in this small community of My Hero Academia SYOCs, and have formulated a few opinions that hadn't quite been present back in December.
I'll do my best to outline them here.
Strong Quirks Don't Necessarily Make Good Characters
I've noticed a trend in Original Characters that I find is adjacent to "Protagonist Syndrome", where the submitter amps up all aspects of a character in order to make them more interesting and appealing. Now, there's absolutely nothing wrong with detailed personalities and busy backstories, but writing a character in such a way that a story's plot and other characters are expected to revolve around them is honestly just a selfish and short-sighted goal in such a collaborative effort such as a Submit Your Own Character story. In most cases, there's anywhere from a dozen to 20 main characters, and attempting to glory hog goes against the whole point of the subgenre, in my books.
Where this ties into quirks is, of course, where the few people who feel the need to amplify their characters rarely leave the superpowers out of the equation. Due in some part to canon having characters with 'boring, weak quirks' like Koda and Hagakure and sidelining them, I've found that SYOCs submitters as a whole have an aversion to making weak/simple quirks. This is likely due to fear on the creator's part that their character will be thought to be boring or weak, and will get less attention from the author they're submitting to.
In other words, everyone's trying to make a Todoroki, or a Bakugo, and the worst offenders create such convoluted and obscene characters that they'd give manga!Midoriya a run for his money with how many powers they have.
Don't be afraid to make simple, uncomplicated quirks if you want! If you're afraid that your character will be overlooked because of that, compensate in other areas! Maybe they've got a super intriguing backstory, or perhaps their personality is so cool that everyone can't just help but be drawn to them. Any author worth their keyboard will know not to waste well-written characters, super-powerful quirk or not.
Science vs Magic
Touching on a point from the first chapter, this is in regards to the "science" and "realism" of quirks. Now I know, I can already hear the "but Chokka, they're SUPERPOWERS, they're supposed to be fantastical!", but hear me out.
It is referenced multiple times in the series proper that quirks are like muscles, physical abilities tied to the user's body. Hell, there's further explanation on that in the form of "Quirk Factors", the biomechanical means by which quirks operate and alter the user's body to adapt to their unique ability. Here's the direct quote from the Wiki: "The term "Quirk Factor" (個性因子 Kosei Inshi?, lit. "Individuality Factor") refers to the collective physical and genetic traits that compose a person's Quirk. This includes the primary Quirk power as well as all the biological mechanisms that allow said primary power to function properly. Quirk Factors also contain a person's consciousness."
(Fun Fact; Aizawa's quirk works by temporarily shutting down the Quirk Factors in people, which is why he can partially affect mutation-type quirks even though they're permanent.)
So while quirks certainly are not 100% based in science and reality, there are clearly limits and basic levels of plausibility one must stick to for a quirk to be a quirk, and not just a superpower. To me, quirks straddle a fine line between "pseudoscientific physiological mutation" and "magic superpowers, with associated physics-defying inexplicabilities", leaning more towards the former than the latter.
And no, background characters with poorly-explained, "magical" quirks aren't the catch-all excuse to go nuts like some people think they are. By saying "don't forget about the magical quirks", you open the floodgates to people making quirks that are practically just magic because there's precedent for it, which should be the opposite of what we want. Most of the reason we perceive these quirks (Such as Manga's) as magical/unexplained is that they come from characters that are so minor that Horikoshi had no reason or time to go into explicit detail.
I Heard You Liked Powers, So I Put Some Powers In Your Superpower
Another topic I wanted to refresh is the concept of a quirk having multiple applications. Now, of course, there's canonical precedent for quirks that can do more than one thing, with Hawk's Fierce Wings being among the best examples. But these kinds of quirks are not the norm, and even if they were, quirks like these with "multiple powers" are often linked very heavily by their thematic grounds, as well as similarity in function.
To take Hawks as an example, you could simply say that every aspect of his quirk is "can manipulate the feathers that grow from his wings". While telekinetic control, flight, and weapon manifestation are all clearly quite different abilities, they are all tied together by a basic ideological premise.
Where I see things fall apart is when people try to take very broad, far-reaching concepts and turn them into quirks. The worst offender I have seen is a quirk called RPG, whose creator shall not be named. (And no, it doesn't stand for Rocket Propelled Grenade.)
At it's base, RPG allowed the user to perceive the world as a video game, with health and energy bars, a HUD, and talent points that the user could spend to alter their physiology. Were this all the quirk could do, it could be salvageable. It still stretches credulity a bit, but by some changes (maybe give the user grow cybernetic parts to become part machine), the quirk could be made to work.
However, it was much worse than that. The quirk had multiple "skins", ways for the user to transform into different creatures that each had different abilities. The first skin was reminiscent of a shooter game loadout, with multiple guns, grenades, knives, and grappling hooks, all with infinite ammo. The second skin was a kind of dragon that could create and manipulate multiple kinds of elements, ranging from fire to electricity to shadows, and more. The third skin was literally a Gundam, a giant 60-foot robot that shot missiles and came with a sword. And if I recall, there was also a skin that turned the user into literal Iron Man.
As one might imagine, the response to this "quirk" was not very positive.
Practically nothing about this ability belied any hint at biological reasoning, every power that it gave had no relation to each other besides "it comes from a video game", and the sheer number and type of abilities were so disparate that there was no logical coherence to it all, besides a vague "uses stamina" stipulation that they all shared.
It was made clear from the first chapter of the manga that no one hero has all the abilities to solve every situation, no Uberquirk that can do everything, and so heroes specialize in whatever field their quirk best suits. (Aizawa in 1v1 nighttime ambushes, Mt. Lady versus giant villains, and Backdraft in fire hazards, for example). Simply put, "RPG" was not a quirk. It was simply a collection of cool ideas smashed together, a square peg being battered into the circular hole of quirks, without any understanding that the ideas of "powers" and "quirks" had any difference.
To sum this section up, here are my basic thoughts on the matter of quirks with multiple abilities.
What it boils down to is versatility versus raw power.
A good sign of a problematic quirk is that it can not only do a lot of things, but do a lot of them very well.
If you're going to have a lot of features, they should be weak individually, and if you're gonna only have one ability, it's okay for it to be more powerful.
Basically, You can have one ability at 100, or five at 20 each, but you shouldn't have 5 at 100, or even 5 at 50.
(The numbers themselves are just abstractions to illustrate the point and aren't indicative of any actual numerical calculations of power, but I hope that gets the point across.)
Power Levels (Should Not Be Over 9000)
I'll keep this section real brief.
When creating a character for a My Hero Academia story, write within the expected power levels of the setting unless explicitly stated otherwise by the author.
If your first-year student is more powerful than Todoroki, the result of eugenics to produce the most powerful elemental quirk possible, you're doing something wrong.
Likewise with Pro Heroes. The average Pro is closer to Spider-Man than Superman. Don't go making heroes that call forth hurricanes or cause earthquakes that devastate whole cities. Common sense, people.
Anyway, I hope you all enjoyed Part Two of the ramblings of an irascible primate on a poorly-defined power system. As always, these are just my opinions, not hard fact. I can only be objectively correct on so much, you know.
See y'all next time.