Pinkie, definitely, wouldn't be surprised for Rainbow Dash or Applejack either. Or Sunset even. Fluttershy though, you'd expect her to have some discomfort with it, yet both versions of her seem to love buttplay. But actually, there was a moment in Holidays Unwrapped where Rarity has Pinkie carry her somewhere, and Pinkie puts her hands on Rarity's butt as she does so. ( Here's a picture of the scene , I think the only edit is the text)As for Chrysalis, she takes pictures of the Main 6's faces, except Rainbow Dash, she takes the picture of her from behind, and maybe it also counts for something that she takes a hair from her tail instead of her mane like she does for the other five, as if she wanted an excuse to get up close behind her again. Then there was the moment where she levitated Tirek in front of her to visually illustrate the part in her song where she says "how bad you got your rear end handed to you". But on the other hand, she did seem uninterested in Twilight shaking her butt in her face. But given how she singles Rainbow Dash out, maybe she's only interested in her and Tirek in that way.