Knuckles is the only playable character in the game that you don't finish a stage with. So what does he say and do when you complete a stage with him? Well, here's how to find out. Select Sonic's Flame Core. Play through it until you get to the part where you take control of Knuckles. Glide to the highest purple light in the room. Turn to the right. Glide onto the wall and climb all the way up. When you reach the top, keep pressing 'A' while moving the left thumbstick up. You'll go through the wall, but you have to start gliding immediatly, or you fall into nothingness. Glide to the left until you reach the ground. Go back if you have to and get the checkpoint. You'll see Sonic there waiting for you. DO NOT TOUCH HIM! Now you can go through the rest of Flame Core with Knuckles!! =)
While in the silver the hedgehog fight go to the top right corner of the map and wait for him to cosmic you out of the passage about 5 to 10 times or lesss and wholla your out of the map but you can't do much though.
Requires Sky Gem. I thought that this was a pretty cool glicth. So at Wave Ocean play through the level until you get to the part before the the whale chase, go to either side of the slope close to the top use the sky orb, charge it, then throw it at the slope and BAM your in space then one of two things happens 1 you die from going to high or 2 you come falling back to earth and still may die from falling into the water. It may take a couple of times to find the right place.
As you may already know, when you are playing the Silver character you press the A button the press and hold the it to glide. Of course you can only glide for a certain distance, but I came up with a way to glide farther. It is simple. Instead of holding the button, you tap it as fast as you can. It way take some practice to perfect, and once you get it right, you can glide a little ways farther, the problem is, is that when you do this, you decrease in alditude. So make sure you are tapping it fast enough to reduce the level of going downwards. Just make sure the place you are going for is not at the level you are already standing at or higher.
First you buy everything for Sonic and you can use the abilities and gems to get around easier. If you don't know how to use the gems I'll tell you how: use the d-pad to select your gem, then press rt to use the gem you selected. You could say this a cheat but I think more of it as a hint.