I feel I should perhaps mention Sailor Aluminium Siren and Lead Crow in the anime, since I didn't see them anywhere else in the thread. I don't know exactly how canonical they are, but there is enough subtext between them to where people frequently interpret and ship them as a couple.
Some people see Michiru as bisexual and I think that's a valid enough interpretation considering she does flirt with men on occasion, but I personally never saw her flirting with Seiya as anything more than a joke. Maybe just cause I can't see her with anyone but Haruka, who is her one true love :3 And Haruka is a definite 100%, Kinsey 6 lesbian... I can't even picture Haruka with a man, can you??? Plus, I love that she and Michiru are a 100% canon couple, confirmed by the creator herself.

I can get behind some shippings like Usagi x Rei (anime) and Rei x Minako (manga), but they aren't confirmed in the way Haruka and Michiru are.
A lot of people interpret Hotaru and Chibiusa as a romantic couple, I think they're just friends in the 90s anime but I can see some support for the pairing in manga and Crystal. Not entirely canonical, but not without any basis either. They're cute either as friends or a couple even if I don't particularly like Chibiusa. Here's one thing I don't understand, though. I have seen some people get SO offended at the suggestion and go all "OMG! THEY'RE JUST CHILDREN, HOW DARE YOU DO THAT TO THEM!" Here's why I think that reasoning is stupid... A young boy and girl can like each other, and no one bats an eye, and Chibiusa has 100% canon romances with male characters in the series in spite of being 8 years old. Why is that acceptable, but her possibly liking a girl isn't? I think it's just that people automatically assume because it's gay, that it HAS to be sexual in nature, which is really rooted in ignorance and homophobia, being gay can be just about love and romantic crushes just like being straight can, and doesn't have to involve any sex. I mean, it's one thing if you just don't agree with the pairing, it's more of a fan interpretation after all, but just that reason by itself is stupid.
I love that Sailor Moon is such a queer show for being primarily centered around a heterosexual romance.

Having at least 6 canon queer characters in a show with an otherwise (more or less) straight cast ain't nothing to scoff at, it may not be actual shoujo/shounen-ai but it's understandable why it has such a large LGBT following. It really did so much for LGBT representation and was way ahead of its time. I think Sailor Moon along with other 90's anime like Utena, CCS, etc., plus early media in general that featured a prominent LGBT cast and showed them in a positive light, helped increase acceptance and paved the way for all the representation we have today. Haruka and Michiru were so amazing for their time because they were a real deal couple and showed LGBT as superheroes and role models and good people in a loving, healthy relationship, for me and I'm sure many others, they were one of the first positive portrayals we had of a LGBT couple at a time when representation was unheard of.