Fixed the hell out of all remaining form problems. Every flavor page should work with no missing sprites. Save perhaps for Unown, because I honestly don't have them. Every sprite exists as ###-form.png. There is also still a ###.png, containing a reasonable default form, so people who don't give a crap about this mess can just use the numbered sprites. Beta forms should now all be ###-beta.png. Form groups now have a notion of "in-battle", which is used to hide overworld sprites when appropriate. Form sprites have a first-class sense of being a default or not, too. Deoxys is... well, let's not talk about Deoxys. Deoxys is fixed.
Added Diamond/Pearl Pokemon sprites.