[Kuroshima]

I would personally change the rule of 16 for the rule of x+4. Attack can at best be 4 points higher than defense. This makes investing on attack worthwhile, but makes even attacks against weaker opponents resistable.

If you find that a 4 point diference is to much, you could say that it's 4 up to defense 20, +3 up to defense 25, +2 up to defense 30, +1 from there over.