The reason I have 2 ground STAB is because of Excadrill's ability, Sand Force. When a sandstorm is in effect, the power of those moves increase by 30%, and with the soft sand, assuming it stacks, would be a 50% increase, so I'm really just trying to make the best out of the soft sand.
Why not set a sandstorm? What if Excadrill is the last Pokemon you have, so you can't set up a sandstorm unless Excadrill has it. Sorry if my grammar was confusing lol.
I'm not exactly recommending Metal Claw over Iron Head. Metal Claw can be learned by level up in every game, while Iron Head can only be taught to Excadrill in Black2/White2, ORAS, and USUM, and not every one has those specific games. I totally think it's better than Metal Claw, but it can't learn Iron Head in the majority of Pokemon games.
Sure the Life Orb is good, but it doesn't need the Life Orb to really make it's moves really powerful. The Soft Sand is just for a boost of power, without any cost. If you want to use the Life Orb, you can, but I would use the Soft Sand.
Both abilities are great, but in this Moveset, I mostly want to max out the power of Excadrill's moves, so Sand Force was the better choice for that reason.
Now I have a question for you,
CAN YOU JUST STOP BEING SO HYPERCRITICAL?
That's all.