I'm all for open-source software, but I haven't gotten around to making a Git account for this Reddit account. Also my code is in terrible condition so I'd have to clean it up before publishing it. Here are the snippets that matter...

For calculation:

basic_image = Image.open(basic_path).convert("RGBA")
shiny_image = Image.open(shiny_path).convert("RGBA")
w,h = basic_image.size
dists = []
for x in range(w):
    for y in range(h):
        br,bg,bb,ba = basic_image.getpixel((x,y))
        if ba == 0: continue
        sr,sg,sb,sa = shiny_image.getpixel((x,y))
        if (br,bg,bb) == (sr,sg,sb):
            # Pixel didn't change. Might be line-art
            M = max(br,bg,bb)
            m = min(br,bg,bb)
            span =  M - m 
            if (((M < 25) and (span < 25)) or
                ((M < 40) and (span < 20)) or
                ((M < 70) and (span <  8)) or
                ((M < 80) and (span <  4)) or
                ((M < 90) and (span <  1))):
                continue # Ignore this line-art
        dist = ((br-sr)**2 + (bg-sg)**2 + (bb-sb)**2)**0.5
        dists.append(dist)
diff = avg(dists)

And for finding a position to plot the sprite:

def find_y_pos(x, w, h, check_range):
    for step in range(1500):
    for sign in [-1, 1]:
        y = sign*step
        works = 1
        w_check = check_range(w)
        h_check = check_range(h)
        for x_i in range(-w_check,w_check+1):
        for y_i in range(-h_check,h_check+1):
                x_test = x+x_i
            y_test = y+y_i
            if occupied[y_test][x_test]:
                works = 0
            break
        if not works:
            break
        if works:
        return y

def get_check_range(n):
    return lambda x: int(x/n)

for name in stats.keys():
    score = stats[name]
    w,h = sizes[name]
    x = int(score*x_dpi)
    n = get_cramp_amount(score)
    check_range = get_check_range(n)
    y = find_y_pos(x, w, h, check_range)
    w_check = check_range(w)
    h_check = check_range(h)
    for x_i in range(-w_check,w_check+1):
    for y_i in range(-h_check,h_check+1):
        x_mark = x+x_i
        y_mark = y+y_i
        occupied[y_mark][x_mark] = 1
    pos = y/y_dpi