Well, a few years ago, I played a Japanese PC J'n'R where you play a ghost being able to use enemies' attacks. But instead of sucking them in like in Kirby, you BECOME the enemy and can use their abilities. Because your character can't fight on his own, you HAVE to control enemies.
The final boss was the character's father controlling a knight, and the REAL final boss was a floating eye kinda like the ones in Yukari's "hole" (connection?).
The problem is, I can't remember the title at all. And I wanna play this game so bad...