Here is a list of loose thoughts, I hope you can find something useful thereWell, the first thing was a lot of practicing. I have studied the poses form the show, drawing many over and over again. And also pone sketches of other artists. There is also a book with many horse poses that I have that helped me to learn how the anatomy is build.The important thing for drawing new poses it that you know how the body of the character is build. Then, when drawing, build it up from the basic shapes - a sphere for the head, one for the chest and one for the hip, then add the legs and other details.It is important to memorize the proportion of the body. Compare various elements of the body - like for a standard pony model the head size is one unit (4/4), then the chest size is 3/4 units, the leg are 5/4 units, the thigh, seen from the side is 2/4 units and so on. You don't have to get everything right in every sketch, but having a general idea helps a lot.Drawing poses without reference - that's not quite true, many parts of those seemingly new poses are things that i have drawn over and over again in practice sketches, or poses are made/mixed from different "known" poses.Some poses may be referenced from real horse poses of even from completely different characters.Some poses can be freely build by using motion lines - you draw lines that express a specific dynamic motion or flow - and then construct the body over them.There are many tutorials for drawing ponies on deviantArt as well.As I said, it took me a lot of practicing - a couple of hundreds of practice sketches to learn how to draw like that. I spend quite some time watching episodes and trying to draw a character in a given pose as quickly as possible, focusing to get the rough dynamic of the pose and the proportions right. After many hours of the training, it took less and less time to finish one sketch and often you could even recognize which pony it was supposed to be