Glacier Beasts are one of the two monsters to be found inside the Aurora Bound Train (the other being Glacier Fragments.) They aren't very strong defense-wise, and one Grounda or Combo should drop them. They have a vicious Ice Needle attack though. That will probably do damage in the high 500s to Kaim, with anywhere from 70 to 350 or so for Sarah -- it seems somewhat random. This shouldn't be a problem except for the last battle in the train, when you'll take on three of these things at once. When that happens some luck will come into play. If they don't do more than one Ice Needle on the first turn you should be fine. If they do you'll probably get a Game Over and have to start the fight over again (you'll only lose a few seconds of your time.)