Gengar, the thing is, in a trainer-lock, it's unnescary. And if you want Uxies, run another Collector. It's near impossible to lock a supporter, while many, many things lock trainers. Plus, you need to have a pokemon in your hand to use it. What if you have none? Or if you have no hand, and topdeck it? A collector would be much, much more useful in this situation.
EDIT: Also, Eleki, the trick is to build up Scizor on the bench. Yes, yes, there is Bright Look/Dragon Rush, I know. Also, you can't OHKO it with extra Defenders, while they can, given enough time, OHKO everything in your deck.
EDIT: Also, Eleki, the trick is to build up Scizor on the bench. Yes, yes, there is Bright Look/Dragon Rush, I know. Also, you can't OHKO it with extra Defenders, while they can, given enough time, OHKO everything in your deck.