Let’s compare the gif and the source image and point out what is wrong:

1. Size. Alex on the gif is the size of a normal mare, while in the source she is size of Celestia. Comes with being an Alicorn, the problem? I am unable to rescale it while keeping proportions and not making it look idiotic (believe me, I tried)
2. Lack of fetlocks. As with the earlier gif of Spex’s ponysona (http://pewnypl.tumblr.com/post/18860453599/ponysona-of-darkly-spectre) I thought I learned how to make them, actually, I was wrong. I can ONLY make the “sharp” ones, not the one Alexis has, so in the end I resigned from adding them altogether…
3. The “cape”. Since I am limited as to which part of the pony I am adding clothing, I had to add the cape (and the vest) to the body itself. And while it looked good on the first frame of the animation, later……. The upper part of the rear leg, it is hiding itself under the body. That’s because, after adding the cape, I had to move the body layer above the leg one…… Hence the result. I couldn’t add a new layer just for the cape, mostly because I would have to move it on every frame in the same way the body moves… I lack patience for that, it would look very odd, since at one point it would be lined perfectly, the other frame it would be slightly off, etc. etc.
4. Clothes altogether - not only there is a layering problem, there was also resizing problem. First the outline - I have NO idea what happened here. With manes, tails, horns, when I’m resizing them, everything is alright. But here? For some reason, while the outline did get larger, it didn’t get thicker, resulting in a very odd… look. Secondly, some rotation problems when trying to put it good with the body, but that is just me giving up at this point.
5. Front leg… The vest is placed ad sized wrong, which with the animation that I have there, creates a really odd “leg moving out of bounds” bug…
6. Wrong eye type, lack of glasses, other small details - me just giving up on it.

So yeah, while I really wanted to make a gif for Alexis, it’s just impossible with my current skill level… And to be honest, I don’t think I will be ever able to get it correctly.