On gimp you can do different layer and save as Gif animation. Then the pictures will more around and stuff, Depending on what you have on the diferent layers. There are tuturials on the web about it.
Aaaaw ♥ ,i adore your pixels esp Piplup, the shading isn't overdone but it still looks good, just really lovely, and nice animations too, i never knew that i can do some on Gimp!