They only work till Gen 5 on BW.
PokeGTS allows you to design your own Pokemon with any move or ability at that time. Once the wifi shutdown, all systems like that came to no use. It only worked for Nintendo DS games, not 3DS. The only reliable source is the powersave (there are a few others too) but it only transfers any Pokemon you want - don't let you design it. That's why many people were very disappointed when the wifi shut down.
Hope I helped! :)