Are Litten and Togedemaru SM08 and 09, respectively? I zoom the image and looks they are numbered like what I am mentioned.
Looks like the booster box won't have 40 packs, since Japanese boxes has 50? now. Sad. English packs must adapt Japanese changes on their packaging. Oh well, The promos were so elegant.
Japanese boxes have 30 packs of 5 cards each. They use to have 15 packs (EDIT doh I mean 20, unless it's a CP). I don't know where you're getting this 50 thing from.
This article is about a free theme deck provided with a comic magazine. It's flying off the shelves too. My friend picked up a copy for me and her son. She said kids were buying 2/3 copies at once.