My daughter has this bought for her this Christmas (2017) - please can I access a valid code? The box was new and sealed - how can thus be ok for the codes to be expired?
Skylanders Battlegrounds originally released in 2012, any stock of the starter packs that retailers have are left over from the shipments they got during that year - it's not Activision's fault that retailers still have stock that they haven't been able to sell yet, nor that there are people who have left it until so late to purchase without doing any research. Similarly, it's usually the rules of the various App Stores that codes can only be "active" for a certain amount of time before they expire, not an Activision decision.
Battlegrounds has also been discontinued, and thus delisted from the app stores, is no longer supported for current OSes.