Cool custom battle system! I liked the choice of using stars to use stronger versions of the skills. Winning battles really depends on finding the enemy's weaknesses and taking advantage of them.
It does take a few goes to learn the system, which leads to the beginning battles to drag out a bit and may overwhelm new players (balancing issues which you have addressed in your other comments). However, once you get past that hurdle, the remaining battles are quite fun to do.
Nice job!