I tested out different Magic Pet Mirror emotes/animations on the PTR prior to 6.2, and there are many pets that /dance, /sit, /cower, etc. A few of them can even accommodate Pepe!
My list can be found on my blog post
. It's not meant to be a 100% full list of all emotes that can be performed while using the Magic Pet Mirror, but it should give you an idea of just how much fun you can have with pet costumes.
I've added Lurky to the list (thanks Madja
!) -- he's one of the pets that I don't own/couldn't test out.