>>34704648>What thematic reasons are there?Ground types are defined by their ability to burrow or otherwise manipulate earth.
Rock types are defined by their tough, rock-like, exteriors or physical qualities.
These two features aren't restricted or synonymous with one another and can appear in dramatically different or contrasted situations and physical adaptations.
The best example I can think of is the numerous Water & Rock types there are: Relicanth, Binacle, Omanyte, Corsola, etc.. Pokemon species that have absolutely nothing to do with ground or 'earth', but have the rock typing because it's a physical quality.
Like wise, you have a number of Ground type Pokemon who, strictly speaking, have no or very little association with rocks: Donphan, Hippowdon, Drillbur, Diglette, Wooper, Nidoking, Piloswine, etc.. All of which are -compared to a Golem or Onyx- too soft n' squishy to be rock, they're just diggers.
That and there's fuckin' Flying types, so whatever, dude.
