The creator of the Applejack seen above (WhiteDove-Creations, aka maker of that amazing Trixie that I was taunted with by everyone for a week :p) contacted the site about it. From the response they received, it sounds like you can still call them "Pony Plushies" and include the character name, but anything specifically relating to My Little Pony has a good chance of being taken down.
Right now there are still a bunch of them available, but for now at least, It's best to keep on the safe side if you plan to sell any in the near future.
Note: As far as we know, this is not Hasbro's doing! Apparently actual community members are reporting these.
Here is a link to the original Deviant Art journal.
And the Ponychan thread discussing it.