Here's what I know: among the 1,000 popular trading-card games, there is one called BATTLE SPIRITS in Japan, that has been going for some time. This year, Bandai thought it would make perfect sense for the next expansion series to be Toho monsters, and here we are.
I bought a set of Common/Uncommon cards, which totals 33, as well as one rare, the Godzilla 2000 card you see above (which is probably promotional, as it says "not for sale"). A lot of the art is pretty impressive, and here are a few of my very favorites so far.
Also, here are the two checklists, if it can possibly help anybody out, since they are in Japanese....but there is a nice picture of Spacegodzilla for the rest of us: