DEF is the most important stat in GFP. Even if you can barely damage the enemy, have a hard time hitting it, and/or you're an easy target from having too low of a SPD, if you can't take damage, that enemy is going down. This very short video shows how this is so handy, including the stats I had at the time (I was running advanced martial arts to cheaply powerup lots of equipment. So, in other words, focus heavily on DEF. Except for a few select enemies, you're fine when you have a high enough DEF.