Someone said that they were alerted to a 'rare spawn' in an area and it was an Eevee.
I can't find anything concrete though. :(
That happened to me this morning in the first quest. A farmer came up to me and told me an Eevee appeared in one of my cities. I only got one Eevee out of the event, so it's not the same as swarms and it didn't have an exclamation point reminding me of its appearance.
I can only assume it's a random occurrence and a rare one at that. Then again, I haven't seen any swarms in the main story yet. --- Fair does not exist. Fair is a word from a world of happy fantasies.
Hm I guess I did misread. D: They were both just rare occurrences after all otherwise I'd definitely have more. :| I'm assuming they're much more rare than the rare occurrence then? --- "Mezawari nandayo! Boku no menomae kara... kie noshimae! Majin Rengokusatsu!"