I think there's an AR code floating around that will give the item and make it work, but you need the AR code on to do (In other words, it will probably crash the game if you don't have the code on).
The Landorus isn't in his Therian forme but I can link you to his Pokecheck page.
http://www.pokecheck.org/?pk=3779006
Also i really hate this event. I feel like Nintendo just completely fucked over some of their player base since not everyone has a 3DS, and 2 of the Therian Formes are actually very good in VGC (Nintendo's Official format) and Tornadus-T is(was) a monster in the singles metagame. (For the record, I only bought my 3DS for Kingdom Hearts 3D, i figured my DS lite would be good for Pokemon for at least another year).