Tonks- genderfluid

Luna- demigirl, Luna in a suit would make her very happy imo

ooooo :D

Cho - Biromantic, can't rlly distinguish between platonic and romantic feelings but just uses the term biromantic for convenience's sake. I also feel she is asexual and sex-indifferent. Probably is cis.

Marietta - I hc she would use the term queer or unlabelled to describe herself but she is attracted to women. I feel she is also aromantic, maybe aegoromantic. Cis.

Severus - grey-biromantic demi-homosexual. trans and is non=binary, I can't think of any xenogenders so I'll leave it at this first.

Lucius - bicurious or heteroflexible, probably allosexual. Questioning his gender but knows he likes he/him pronouns.

Percy - cupioromantic and demi-bisexual. Masculine but doesn't really know his gender. Also has specific terms to be addressed by.