do you possibly want to take off the other pokemon before the one appearing?, im not sure about the programme your using, as ive never used it, but see if it has a layers sytem, if so , for each frame only let the layer of the new pokemon show, taking away the last one, and any before that.
my one has about 10 layers, as its small, but has like 40 frames, which isnt that much considering that a tv shows about 50 frames per second...