Today the second game for the Datach Joint ROM System was waiting for me at the post office. I’m glad to have found it for a decent price as these mini cartridges and barcode cards are quite rare and/or pricey.
Ultraman Club: Spokon Fight!! (ウルトラマン倶楽部 スポ根ファイト!!) is a track and field / Olympics game with characters from the Ultraman universe. It contains a Datach mini cartridge and 40 barcode cards (including two blanks).
The Bandai Datach Joint ROM System is an add-on for the Nintendo Famicom. It plugs right into the cartridge slot and comes with its own small cartridges. The games are enhanced with barcode cards, similar to the Mattel HyperScan.
The retail package with one included game, Dragon Ball Z: Gekitō Tenkaichi Budokai, is rather easy and cheap to obtain.