Okay, I was on episode 5 and I was stuck at the Plunge with Kygar.(I had pretty poor stats, BTW) I just coudn't seem to beat him. He always used the skill(you know, Cross Sweep, Drop Slash) that would beat me, so I tried beating him without using any risk attacks. It didn't work.
I thought about it for a while, and decided that it probably uses some kind of logic. The skill the enemy chooses depends on what both you and the enemy chose last pass.
I can't remember the logic I used, unfortunately. But it helped me to beat Kygar using a Risk Attack every turn. I won with a Weak Victory(I had very poor stats).
I'm not sure if this is true or just a coincidence, but it's strange how I was only able to do equal amount of damage to him as he did to me using this logic.
Maybe those of you who know how RM2K works can figure out if this is right or not.
