There's also Idun. From Gaim Gaiden, who's red.

hey, hey, do not insult the Hefty flexbag cape.

Why does his arms change from red to blue when e wears the cape? What makes the difference?

Red flare was an incomplete form so to say while the blue form represents that the eternal memory was with the compatible person.

Oh. Ok.

As SanoBaron demonstrated, the only pink and white rider suits for females are Marika and Femme. And it makes sense, because their motifs are a peach (pink) and a swan (white).
What's wrong with pink and white anyway? I like pink.

You forgotten kivala from decade

Nothing is wrong with white, but pink is stereotyping the female character into what is perceived as a "Feminine" color.

Kivala is white and purple, which would be going against what Sano was trying to disprove.

I think white would be fine for a female Kamen Rider considering there's plenty of male riders who are mostly white, meaning it can be considered a gender neutral color for that series.

Fourze, Mach, and Ixa for example.

even Den-O is mostly white in almost all of his forms.

Would it really be stereotypically feminine in a franchise where we already had a male character with pink/magenta-colored armor?

Pretty much.