You’re right about Minako being completely straight in the 90’s anime but none of the other Inners are straight in the 90’s anime. Mako is outright canonically bi since she has that one episode of crushing on Haruka while knowing she’s a woman, Ami is likely bi/pan too since she blushed when she first met Mako and is ship-teased with her a lot. Rei is likely bi since Ikuhara was gunning to ship her with Usagi, she flirts with Haruka even after finding out she’s a woman and we have this totally heterosexual scene here:
To say nothing of Usagi who blushes when she first meets Rei and still continues to harbor feelings for Seiya even after finding out about their genderfluid status. In the Manga however Mako and maybe Ami appear to be the straight ones, Mako is also the only straight one in PGSM.
Setsuna is actually one of the girls I would ping as straight because of her unrequited feelings for Endymion and no one else. This only applies to the Manga and Musicals of course, whereas in the 90’s anime she honestly reads as aro-ace. I could see her potentially being into women though since the fandom likes to headcanon that she’s in a Poly OT3 with HaruMichi, especially in the Manga where all three are wearing wedding rings.
Hotaru is obviously WLW and might even be an outright lesbian in the Manga since we see she clearly has feelings for Chibi-Usa there and no one else, meanwhile I think she might be straight in the 90’s anime since her ship-tease with Chibs is toned way the [BLEEP] down and there’s that one episode of her clearly crushing on that male star athlete.
Chibi-Usa is bi/pan in both 90’s anime and Manga/Crystal (in the 90’s anime she crushes on Tamasoboro when she thinks he’s a girl and in the Manga/Crystal she has her thing with Hotaru) and Mamoru is also potentially bi/pan in the 90’s anime due to his connection with Fiore and they would’ve probably gotten together at some point if Usagi had never come into his life.