Though in all truth we don't even have to worry much about Glaceon or Leafeon, they are available in the Dream World.
Otherwise I bet they are Sinnoh Ice & Moss rocks only myself, hence why they are in the Dream World in the first place.
The electric cave seems highly likely for the magnetic evolutions though. ^^;
Have they been confirmed to ALWAYS be in the dreamworld? I thought it made out that you can only get one eeveelution from there, through the special-thingy.
I hope there are fixed places in Isshu for this kind of thing :\ I like the idea of a Rock which changes with the seasons like someone mentioned above.