Using the function pbFrameUpdate(nil) is what you're looking for. This function updates the sprites and the battle boxes of the various Pokemon, now you just have to insert them in the right place. Some are more obvious than others. Just do a quick search for general updates in the battle system, and you'll know where to put them. One of the updates that you were looking for is within def pbAnimationCore. There you'll see a chunk of code which looks like
With all this said, again, I will refer you to a post I made a while back.
Is this what you were asking for Maruno?