>>52883886I was thinking Ghost/Fighting but actually you're right, Lucario having neither of its original Types is more interesting.
>>52883897Because both Types are associated with deserts and/or Egypt stuff in various ways. For the most part, sand/desert is represented consistently by Ground Type in Pokémon, the only exception is the actual move Sandstorm itself because it was synonymous with Tyranitar at the time and Rock Types are the ones who get the defense boost. All other sand-based moves are Ground and various desertmons like Flygon and Sandshrew are Ground
But of course pyramids and ancient monuments are made of stone. Really Ground or Rock would work fine, they're both symbolic of the desert.