In Mossdeep City there is a house with a door that is locked. What is behind it and how do you get in it? Also in Fire Red there is the same house in Island 7 and there are boxes covering the door. Whats behind it and how do you get in?
You need to scan Battle e-cards in an e-reader and then you'll be able to battle trainers behind those doors. The e-reader and RSE cards are no longer being produced so they're quite hard to find. The FRLG cards were also never released outside Japan.