Art Pony Pose
Also known as the Core I pose.
The body of this style of pony was designed to fit with a range of plastic molded clothing, and to denote this the (non-Event and non-Art) ponies had a coat hanger symbol as their hoof mark, rather than the usual G3 Hoof Heart.
The same basic body shape can be seen in a Unicorn version of the pose, Sweetie Belle Pose, and the Pegasus version, Star Song Pose. The same body but with different head mold could be seen with the Makeup Scootaloo Pose and Makeup Cheerilee Pose.