The GTS has a filter that blocks hacked pokemon from being traded, so that would make all those people wanting "level 9 and under Zekroms" unable to get one. I had a Mewtwo I got from Fire Red that has Thunderbolt, Recover, Shadow Ball, and Psychic. I caught it in Cerulean Cave. It and a lot more pokemon I got legitly are apparently "hacked" by Black 2's GTS...