I have had a total of four 10k eggs that I have hatched. Out of those four, 3 have been Eevees and 1 Scyther.
Now in my, likely shared, opinion Eevee is the worst thing to get from a 10k egg. But in fact (I believe) it IS the most common to find outside the egg. Does that commonness have any relation to how common they appear in my 10k eggs, or do I just have bad breeding luck?
