You’re most likely referring to the Japenese promos BW25-31, namely Druddigon and Emolga. You can read about them in this discussion here:
www.elitefourum.com/t/bw-p-25-31-never-issued/13361/1
For further information you can see:
This 2011 thread on the cards that temporarily appeared for sale before being removed and the listing cancelled:
www.elitefourum.com/t/10-000-promos/10240/1?page=1
This 2012 discussion on the same cards:
www.elitefourum.com/t/what-happened-to-bw-p-promos-27-31/10573/1