Final Submission - Sand Serpent
It's based on a sea serpent. But isn't this supposed to be a Rock type, you may ask? Yes, it's a Rock type. A sea serpent which doesn't live in the sea. Instead, it freely swims through sand.
As for the main concept, it fits rather well. It clearly looks like a Rock type. However, it looks as if it could be fast, with a thin, streamlined body. And it could easily be a capable special attacker, with gemstones in its body amplifying its power. I can envision it using a wide range of special attacks, such as Flamethrower, Earth Power, and of course, Power Gem. Also, unlike most Rock types, it lacks arms and legs, suggesting that it's not much of a physical attacker. Granted, it looks like it could fire off an Earthquake or a Stone Edge, but then, so can many other special sweepers, such as Latios or Heatran.
About the design changes, I decided to repeat the rugged stone section on its head further down the body. This made it look more natural. Also, I replaced the orb on its tail with a blade, as was suggested. This gives it a more streamlined appearance, suggesting a high Speed stat. Finally, I changed the colour scheme, as some people said it looked too much like Giratina, and others too resemblant of a Ground type. I feel I've managed to address those issues.
Well, good luck to everyone. I'd also like to add that I did this because I felt many of the other designs were too un-Pokémon-like. This is still the case, but to a lesser extent. After all, it's hard to envision a Rock special sweeper, is it not?