With Amy its easier because thats one of the levels that she needs to go to.
A2:
You have to find Amy Rose then go to Twinkle Park. -Answer by:1420
A3:
Go to station square look around until you see a big ball on top of the thing next to that sewer that little tower with the big ball on top of it is twinkle park go on the elevator on the bottom of the tower and the elevator is round on the floor
A4:
Only Sonic, Amy and Big the Cat can actually play a Twinkle Park action stage. The other characters just play the Twinkle Circuit mini-game.
If you mean during story mode, then what you have to do is wait for the scene where E-102 releases you, then exit the prison hall. You will be in a room with a platform that says "HIGH SCORE" in big letters. Jump on this platform and you will hear a buzzing sound. Then you will be playing a game like whack a mole. Kill the blue and yellow hedgehogs but not not the Eggmans or you will lose points. If you beat the score you can leave the room and you will go into the hot shelter. If you beat that action stage you will just have to watch more movie scenes and you'll be out in no time!
First you have to beat the casinoplis stage then it will apear in a ally near it -Answer by:lilmouse
A2:
after you beat the casinopolis stage walk around the corner into the alley and pick up the blue crystal and take the train to the Mystic Ruin's and you will see the new cave. Just hold the crystal till you come to the ice cavern and place the stone in the holder. Jump in the water with Sonic and get his new ability. Then jump out of the water and go up the ladder. Be very careful. You will get to snowboard a good bit. -Answer by:zorbak80