Oh, you want an animated battle background. You could use a constant "battle animation" call to try and give the effect of animation, but there's a good chance that the player could wait it out and the animation would stop. You'd really have to try and extend the battle animation out really far for it to last that long, and it would look wierd transisting over each turn...
I can't really think of a way to do this, to be honest, I've never tried to do it before. I will say this though, you can't use a Parallel Process since that would only be in effect out of battle,