Sailor Moon, along with Cardcaptor Sakura, was groundbreaking for really being the first kids aimed media to feature prominent LGBT representation and queer themes.
I guess I'll start off by posting off my queer headcanons for the Senshi as well as the canonically queer villains.
Usagi: Bisexual, Panromantic and polyamorous in all versions.
Ami: She's kinda hard to categorize, most would go the ace route but in early manga chapters she was shown to have an attraction to Motoki, and then of course there was her whole relationship with Greg/Urawa in the anime and she even seemed to have a crush on Usagi in PGSM. I'm just gonna go with Fluctuating/Evolving for her, she's too hard to pin down.
Rei: Bi in the 90's the anime, lesbian in PGSM and a demisexual panromantic in the manga.
Makoto: Established as canonically bi in the 90's anime but is interestingly enough one of the straighter Senshi in the manga and PGSM. So she's really only queer in the original anime.
Minako: Bi/Pan and poly, she's the Goddess of Love for Venus's sake! I also think she might be aromantic, or at the very least demiromantic which is ironic cause people usually think to assign that label to Rei, but to me, if you really look at it Minako fits it better.
Chibs: Bi
Haruka: non-binary lesbian, is there any other option?
Michiru: In the manga I headcanon her as a demisexual lesbian, however in the 90's anime I see her as bi or maybe homoflexible (still demi though) since she did flirt with Seiya before knowing about their female Senshi form. I know it wasn't serious but lesbians never flirt with men, even as a joke.
Setsuna: In the 90's anime I think she's ace and aro, in the manga and musicals she's demi and pan.
Hotaru: Bi in the 90's anime, lesbian demi in the manga.
Mamoru: Demisexual panromantic
The Starlights are all canonically genderfluid/some manner of trans in the anime and Seiya's feelings for Usagi so they're all queer there by just default, I headcanon that only Seiya is a lesbian in the manga though.
pro
Kunzite is bi, Zoicite is gay in the 90's anime and bi in the manga and musicals.
Nephrite, oddly enough might have some trans leanings if you go by the manga?
I headcanon 90's anime Fish-Eye as a transwoman, sorry not sorry, the DIC dub was right to change her pronouns, fight me!
Hawks Eye (and possibly Tigers Eye?) are the trans ones in the manga though.