Timed hits in multiplayer

I am working on creating a multiplayer rpg with some pvp combat included I would love to do timed hits in much a similar manner as is done in paper mario or super mario RPG but the problem is I can't for a life of me think of a concrete way to prevent client side cheating. I can imagine players using all sorts of timing bots and what not. So I am left with either not doing timed hits at all or make them more minor. So I guess i am wondering just How would you recomend to go about protecting against these sorts of exploits.