This build for the most part is fine, a few things though, you want to start with spiritomb, so why play 4 gligar? You only need three gliscor's out at the most, also unown G should be a tech you're using against if your opponent should attack with chatot, and that shouldn't be happening a lot so the G is not that important. Also I know it sounds sort of bad, but BTS is really essential to the deck, and I think you should run 4. As for the extra spot, running a great ball would be nice, this deck does need a lot of basics out really fast.
So essentially:
-1 Gligar
-1 Unown G
+1 BTS
+1 Great Ball
For my build it would be this:
-1 Gligar
-1 Unown G
-1 Cynthia's
-2 Warp
+1 BTS
+4 Great Ball
Although I am considering warp energy in case spiritomb does get locked into active, so I could see myself going 2 and 2 on the great ball and Warp.
As for what Banzai suggested with Luxray, when I first made a glisctomb build, I designed it to get prizes as well as locking, with poison and crobats. The luxray was to keep a constant GoW working so that the opponent wouldn't bring up an unevolved pokemon to get past the paralysis, and the crobat was to get around pokemon with odd hp, because you also needed the poison to KO your opponent's active when it became your opponent, or else they would be ready to attack on their turn. I still ran unown K for when my opponent figured out what I was doing, I never let anything get KO'd until I was ready to bring up another pokemon to lock. But to come back to the point, Luxray is for this kind of build when you need plenty of GoW support, but if you're just going for the lock then pokeblower's should be enough, although it would be interesting to switch it out.
Such as:
-4 Pokeblowers
+1-1 Luxray
+2 Poketurns
To make your build into what I originally had it would be this:
-4 Pokedrawers
-2 Warp Energy
-1 Gligar
-1 Unown G
-1 Chatot
+1 BTS
+4 Poketurn
+1-1 Luxray
+2 Crobat
The idea isn't exactly to win via prizes, but just to make sure that your opponent doesn't win because they got some early ones.