Oh I dunno, Flutters has had some rather Yandere moments towards animals, especially in "The best night ever"

"YOU'RE GOING TO LOVE ME!!!! D8< "



Plus Pinkie in a Party of one had that whole mental breakdown after perceiving rejection, which is a big trope with Yandere.



It won't ever go bloody or "Cupcakes" levels of crazy, but there have been moments. In my opinion anyway :3