Pokémon Tretta Lab will no longer be listed on the Nintendo 3DS eShop as of 17:00 JST on Wednesday, August 31. This piece of downloadable software was only available through QR code in packaged editions with its included hardware. It served as a database utility that interacted with the Pokémon Tretta arcade game’s pucks by scanning them using the 3DS camera and displaying data. It stopped being supported and sold in 2015 and wasn’t functional on the New Nintendo 3DS.
Source: Serebii