I still can't figure out what the heck I'm supposed to do, I swear you need two people for one part. I figured out so far that the bubble shields are meant to trick the traps and thus you avoid getting SMASHED by huge rocks. There's only 1 on the left path, which I think is the easier way to go, because there's no risk in getting damaged. However when you get to the inner room and go right... I don't know what to do as I can't get up to the next floor as it's too high and I don't have any grenades >.<