On the same floor as the robot guarding the doll (they're normally called Poyozo dolls), you have to find another robot that's exactly the same as it...it should be near the topmost of the area. It might take some exploring via "secret" wall passage (i don't remember exactly)...well, anyways, once you get to that, you just talk to it and it'll follow you because you need to get it in front of the first robot so that they just freeze each other...that way you can get your doll. TA-DA! You may also have to charge Robo in order to open a door or some junk to get to that second robot...it's been a while since I've played that bit, so it's kinda sketchy in my mind.
MagilsugaM, he's just asking for advice on a part in Chrono Trigger...I don't know wtf YOU'RE talking about...>_>