Here's a interesting fact about the Japanese box promos. While they are alternate arts of a holo in the set, there's something else I've noticed.
BW4: Volcarona
BW5: Ninetales
BW6: Flygon
BW7: Crobat
Volcarona is Gen 5, Ninetales is Gen 1, Flygon is Gen 3, and Crobat is Gen 2. It may...