So for the game I'm making, I decided to use the Black/White animated sprites for Pokémon, so what I did was write a program that converted the GIFs into a long PNG file which contains all of the GIF's frames. Right now, I've only got the generation 1 Pokémon, but I may add in generation 2. Shinies are also missing, I'm planning on adding those too.
Here are the sprites I've converted:
to
Here is the .exe for the converter. This will actually work for any GIF, provided the output format is the one you're happy with. (you just need to download the gifs, place them in the proper folder and run the program)
Here is the source code if you want to change the format (C#):