In order to get Joltik, you need to go to the northern part of the Aventurine Woods at night. Head to that part where there are three or four webs between trees.
Eevee can be found in Spinel forest I believe, but it requires windy weather and maybe it has to be night time, but I'm not certain of that.
Drilbur has a 1/18 chance of hatching from your mystery egg