A lot of Generation V move images (and move images in general) fall under the Category:Images needing to be animated category.
That's not the problem; the problem is that for most moves (at least), the resulting image's file size is much too large for the archives to handle. I did an animated V-create a while back, trimming it to only the absolutely necessary frames (ie. no HP bar or whatever), and the animated PNG turned out to be over 5MB @ 60 frames (I'm assuming 30 frames results in a smaller file size, but for Generation V at least, I'd like to stick as close to the game as possible, and that means 60FPS for battle images).
I think this would also be a problem with the more "flashy" G4 moves (Draco Meteor, Judgment etc.), which use 30FPS; the only way to resolve this seems to be increasing the filesize limit from its current 2MB limit. Either that, or we don't use animated images for "flashy" moves.
I don't know if PNG compressors work with animated images; if they do, I'll use them, but I don't know how far the compressions can go without losing quality.