Hi! The Game Corner is a casino. You can bet on slot machines and win coins. You can trade in the coins for great prizes next door. The prizes are pokemon: Clefairy, Abra, Dratini, Scyther (red version), Pinsir (blue version), and Porygon. Each pokemon has different value in the two versions. For example, Porygon costs 9999 coins in the red version but only about 5500 coins in the blue version. You can also trade the coins for great TM's. You can keep on betting and hope you win. Remember, coins are not money. They are casino money. You don't bet money on the slot machines. You bet coins. You can get coins from people in the game corner if you talk to them. Also, you can walk around in there pressing A. You'll pick up some coins. First, you need a coin case to hold the coins. You get the coin case in a building that looks like a restaurant inside. There, a man lost all his money on the slot machines and happily gives the coin case to you.
Talk to all the people in the game corner and you'll get 50 coins in total. If you have lots of money, talk to the man on the left corner (not the woman). He will give you 50 coins for every 1000 dollars you give him. I advise you to do this because winning coins on the slot machines is pretty hard. Anyway, you will see a person guarding a poster at the top. He's a member of Team Rocket. Fight him.
When you beat him, press A at the poster. You will press a switch and a secret doorway at the very top right corner will appear. Go into it.
Go in. Don't fight anyone yet. Instead, immediately go the flight of stair on the right. Keep going down the flights of stairs until you can't go down any more.
When you are in that room, go to the top left area and you will fight a person. When you beat him, he will give you the Lift Key. The Lift Key lets you control the elevator located at the bottom right.
Go back up to the very first floor and fight the trainers. Go down one flight of stairs and fight the stairs. Go past the maze thing. Get the items.
Don't go into the elevator yet. Go to the stairs first and fight the people. When you have fought everyone, take the elevator up to the 4th floor.
Beat the members of Team Rocket there. Finally, fight Giovanni. I remember he has a rock pokemon, and Kengahskan. Maybe, something else too. Anyway, make sure to bring a water or grass pokemon. Bring a psychic pokemon too. When you beat Giovanni, he will give you the Silph Scope. The Silph Scope will identify the ghost pokemon in Pokemon Tower of Lavendor Town. Take the elevator back to the first floor. Fight a trainer and the door will open. Get out of Game Corner. Fly back to Lavendor Town.