I was thinking about something similar the other day, except they would be "tactics", basically certain styles of battling /strategies /battle cries that can be used a limited amount of times to give an advantage; these would be classified on levels depending on how strong they are, and you would need to spend a certain amount of "points" to use them (higher level=more powerful=more expensive), these points would be limited per battle, so you can either use several weak "tactics" or spend all of your points in a few, very strong ones. Effects would basically include stat boosts, reducing/increasing damage of certain types/categories, certain status move effects (taunt, defog, protect, etc) and maybe even allow you to summon a certain Field Effect during a limited amount of turns. The player would start with only the most basic ones and then acquire more of them as they defeat the trainers who use them (in the sense that you're learning and assimilating their styles into yours).