Flygon: The original Garchomp. It's dragon abilities are very lacking. By level up, its strongest dragon move is dragon tail, with 60 power! Its ground powers, on the other hand, are what makes this guy awesome. Two words: Earth power. Lowering the opponent's special defense is a bonus. Its levitate makes it immune to the annoying move Earthquake, which makes a good counter. Its main weakness? Poor special defense.
Garchomp: This guy is an annoyingly ripped Flygon with bigger stats. But its weakness is its movepool. Its ground powers are awful, so it has to rely on dragon moves. Most aren't that powerful or come with grave effects. But! Dragon Dance can turn crap moves into awesome moves. The catch? It uses a turn, making Garchomp vulnerable to attack. But the speed boost helps, and this ploy has been used a lot.
So, in the end, who reigns the world of ground-dragon types?