you unlock the APC
there is no sepcific way to unlock them. you just keep playing. i have unlocked some mostly playing my player and the Jordan challenge's/MJ: Creating a Legend.
you can go to kanto and get all the kanto badges. that will unlock mt. silver, which you can climb to challenge the trainer red.
To unlock the Gym door in Sootopolis City in Pokémon Ruby, you need to first defeat the Elite Four and become the Pokémon Champion. After that, return to Sootopolis City, where you will find the Gym door will automatically unlock, allowing you to challenge the Gym Leader, Wallace. If you haven't defeated the Elite Four yet, you won't be able to access the Gym.
you can challenge them after you get the first 8 gym badges
No, it does not. you can challenge the Elite four as much as you like.
find the guy with the red hat in the woods and challenge him 2 a duel if you win you unlock an ultimate Pokemon then you move on in the game. (vid part 1)
You challenge the Elite 4.
To unlock Groundon, you must beat the Elite Four and talk to the weather man.
no you can only get an elite puffle if you own the game herberts revenge and unlock the hat for a black puffle
You need to wait until later in the game when you are in races against the special cars that you can unlock during the game (like the Logitech Racer and Elite Racer).
Look at the bottom right corner of the map. The elite four can be found there
You unlock it in the further game difficulties.