Depending on where you are in the game (I figure you're pretty far considering your levels), I would suggest Nidoking or Nidoqueen as a Ground-type. Partly because of their Poison half, partly because of their moveset, but I like them.
Let's consider some other Ground options for a minute:
Golem
Onix/Steelix
Dugtrio
Sandslash
Rhydon
Marowak
Gligar
Piloswine
Quagsire
Call me crazy, but between those you can find one without having to hassle with trading in RSE.
Now here are my reasons for giving my suggestions.
Golem: Not really that good. Great defense, but an incredibly common weakness (4x to Water)
Onix: Same as Golem, and for Steelix: Crappy Special Defense, but you could use that...
Dugtrio: Ever since Gen 1, this is useless, basically.
Sandslash: The ability to learn other moves than Ground, but not the best by stats.
Rhydon: Another good choice, I should have mentioned it above. Same weakness as Golem though...
Marowak: Similar to Dugtrio and Sandslash, not effective anymore.
Gligar: Strange hybrid, hard to use.
Piloswine: Great hybrid, that's another possibility, but I still like Nidos better.
Quagsire: Maybe this would be okay, but its hybrid makes you very susceptible to Grass attacks.
So my final answer? Nidoqueen, Nidoking, or Rhydon.
Hope this helps!
AEPMT
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