Geodude -> Graveler -> Scrystal
It bothered me that Geodude completely lacks the whole "geode" aspect of its namesake in its design. So I designed a regional line based on geodes, "splitting headaches", and crystal balls. I will likely be adding more minor details to Scrystal to fill in some of the empty space, but for now this is what I've got.
Geodude from the (x) Region live in caves overflowing with dense psychic energy. As they absorb the psychic energy, large crystals form inside of it until they eventually rupture and break open.
(x)ian Graveler are able to provide brief glimpses into the near future. These visions, however, are cause Graveler pounding headaches, so the visions are often incomplete and ultimately unhelpful.
Refinement of its immense psychic power led to the evolution of Graveler into Scrystal (Scry + Crystal). Scrystal are highly sought after as their ability to show visions of the future to people in the orb on their back is very useful. However, the visions they produce are triggered by influxes of psychic energy. Mediums that possess psychic powers are able to draw out the full extent of its abilities on demand.
by SammSandwich