Ōishi Kōji is a Japanese manga artist, best known for creating the series Inumarudashi. It is presently not known if he has any role in an official capacity, relating to Pokémon.
In his Super Secret Base, his battle team consists of a Mega Salamence, Azumarill & Heatran.
As this is a special Super Secret Base, it can be found in the locked back room of the house south to Mossdeep's Pokémon Center.
This QR code was made available at the Jump Festa 2015 in Japan. Thanks @BlackShark for helping the site archive this.