Hero of Pizza
In the US, the codes for Marshadow will be available at GameStop stores from October 9th until October 23rd.
However, the codes will be available at participating retailers in Europe for much longer: from October 1st until November 16th. No details have been shared yet on which specific retailers in Europe will be giving out the codes.
Not only will these codes (which can be redeemed on your copies of Pokémon Sun and Pokémon Moon via the Mystery Gift menu) give you the previously unobtainable legendary, this Marshadow will also come holding its unique Z-Crystal, Marshadium Z. When the Z-Crystal is used Marshadow's signature attack Spectral Thief will become the powerful Z-Move known as Soul-Stealing 7-Star Strike (which we previously reported on).
The stats for this Marshadow, which are the same as the Japanese distribution, look like this:
Held Item: Marshadium Z
- Spectral Thief
- Close Combat
- Force Palm
- Shadow Ball
If you live outside the US or Europe, let us know in the comments and we'll try to help you figure out if/when the distribution will be coming to your home region as well!