I have been meaning to show this and ask for some advice. I tried my hand at scaling sprite pools. You will probably make fun of my technique but I managed to maintain the scale of hidden and shown sprites! Which is tricky because the pool expands and contracts meaning the sprite scale of the hidden sprite can be applied to a non-hidden sprite if you are not careful! My only issue is jitter where the scale digression progression is choppy and not smooth. A standard scale in my mind should smoothly scale on the center point of the sprite. I belive the jitter is from slightly different x,y values on my way up and way down.

I will prepare a small demo and release it on this thread in a few days. Hoping HPMAN can give me an A for effort.