Saw the passive abilities question, so now we have to ask: what passives would all the golds have?
I am SO sorry this took me so long to answer, but here I go!
Of course, I went the "creature the zodiac sign is linked to" way.
Aries:
You know how rams headbutt each other to assert dominance? The Aries Saint has the ability to headbutt people without gaining brain damage as a result. Well, jokes aside, rams can charge at incredible speed before attacking and have considerable endurance, so maybe the latter is what I can give the Aries Saint as an innate ability? Fights between rams can last for hours, so I bet the Aries Saint can keep fighting for much longer than a Saint normally can.
Taurus:
Rather than an ability, I would say the Taurus Saint has a tendency of being red-green colorblind, as bulls generally have dichromacy. In addition to that, I'd say the Taurus Saint is always the strongest, at least on a physical level, because bulls have incredible strength.
Gemini:
Well, I don't know? The gemini zodiac sign literally represents twins, so... I have no idea what kind of ability I could give the Gemini Saint, aside from an innate capability of bickering with their twin.
...
Okay, I'm done joking. Gemini represents Castor and Pollux, the Dioscuri, who are known for being excellent hunters and horsemen. With this in mind, I'd say the innate ability of the Gemini Saint is exactly that: riding and hunting. And this Saint can hunt anything.
Cancer:
... I thought I had no idea of what do write here, because, well, the constellation is literally just the crab that bit Hercules while he was fighting the Hydra. There's nothing associated with it, save for this fact, and that it was placed among the stars by Hera. But then I remembered that I'm supposed to take into account the animal itself as well, and crabs? They can themselves so well you can't notice them even if you walk right past their hiding spot. So this is what the Cancer Saint's ability. Hiding. Which, if you ask me, is an extremely useful ability, no matter how proud the Gold Saints are.
Leo:
I wanted to say "the Leo Saint has the ability to run after a laser pointer" so bad, but then I remembered that one video I watched of lions being completely uncaring of laser pointers so... guess the joke died before existing. Anyway, the Leo Saint is probably known for ability to deliver short but powerful attacks, just like real lions. They don't have much in terms of stamina - remember, we're still in the superhuman category here - but they are powerful by default. Also, using the Nemean lion to my advantage, I'll say the Leo Saint can't be wounded easily. Just for a silly comparison: if another Saint lands face-first into the ground, there's going to be blood right away; is a Leo Saint lands face-first into the ground, there's still going to be blood right away, but only because Leo would kick in the teeth whoever slammed him on the floor. Basically, it takes effort to draw blood from a Leo Saint.
Also, a Leo Saint that's also a woman has a more refined hunting instinct, because I watched way too many documentaries in my life and I know that a lioness does 99% of the hunting work and it's better at it.
Virgo:
Does the ability of never getting laid count?
This one is tricky, because Virgo represents Astrea, the celestial virgin and goddess of innocence, purity, and precision. Since these don't really qualify as abilities, I looked into her mythology and remembered that she's closely associated with Earth. Because of this, I believe the Virgo Saint's ability is to communicate on a deep, spiritual level with the essence of Earth and its creatures. Which is not too far from what's actually depicted in canon, after all.
Libra:
The Libra Saint can always find the perfect balance. Doesn't matter if it's physical or metaphorical, Thanos would die of envy for how perfectly balanced everything is for this Saint. Aside from this, which is more of a practical ability, the Libra Saint has also the amazing capability of being always able to find loopholes in laws (Libra represents justice and law, so... yeah), and can always know if someone is innocent or guilty.
Scorpio:
Oh, here I go, let me butcher my sign completely. My first thought was that the Scorpio Saint is actually venomous (god, I hope I used the right word, we only have ONE in Italian for poisonous and venomous). Not like a certain Pisces Saint we know and love, of course. Just like with Taurus, it's a characteristic and not a passive ability, but I do have something else as well.
And that something else is an ability to survive even in the worst, most dire conditions. Scorpions, unless you straight up crush them under your foot, are extremely difficult to kill. They have a tremendous immune system, they literally don't drown, they can slow down their metabolism when there's no food around, you can freeze them completely and they'll just walk away once thawed, and they can live in harsh climates with no issues. In light of this, the Scorpio Saint is extremely difficult to kill, and can resist most life-threatening conditions with ease. I'd say is a good passive ability to have, for sure.
Sagittarius:
It goes by itself that the Sagittarius Saint has the innate ability to be absolutely amazing with bow and arrow, but another passive ability they have is horse riding. Lastly, since the constellation actually represents Chiron, the Sagittarius Saint is an excellent mentor and teacher, better than anyone else.
Capricorn:
Goats can climb near vertical surfaces, and so can the saint of this constellation. It's a really useful ability, especially when it comes to stealthy missions and the like. Alongside this, the Capricorn Saint is probably a really good swimmer, since the constellation is half goat and half fish, although not as good as the Pisces Saint.
Aquarius:
Oh, here we have some troubles. The Aquarius constellation represents Ganymede, Zeus' freaking cup-bearer. He's a hero, yes, but he's known for having enchanted Zeus enough to gain a place in the Olympus as an immortal. What does this leave me with? A Saint that has the air association of the sign, the water association of the constellation, and the fascinating beauty of the myth.
Let's just say that the Aquarius Saint has the perfect mastery over ice (which is canon) because air and water? Come on, it's the only thing I cant think about. That's the passive ability, an insane control over water and air that translate in mastery of all ice things. Plus the ability to enchant even the gods, because the Pisces Saint is not the only enticing person of the Sanctuary.
Pisces:
I'd say the passive ability of the Pisces Saint is swimming like a mermaid, aka quickly, efficiently, and without needing as much rest as a normal human. Some powerful Saints can also find themselves able to breathe underwater, but it's a rather rare ability that doesn't show up often, and not many are willing to try breathing underwater just to make sure.
And that's it, since the other somewhat passive ability I love to give every single Pisces Saint (and not only the canon ones) is venomous blood and plant toxins immunity.
I don't know if I nailed or failed this answer. I'm mostly going off of stuff I know out of the top of my head, because I'm a sucker for nature documentaries and documentaries in general, so there might be some stupid things sprinkled here and there.
Doesn't matter.
Once again, sorry for taking so long, and thank you for the interesting ask!
