On many Xbox 360 games, the game security is very strict. If you modify one file of the game, it can no longer be booted up. This is not the case with Sonic Next. The only file left protected is the game executable itself. All other files are freely editable and bootable on the 360. By swapping characters, such as regular characters with amigos, we can see that they in fact have their own animation in the character select screen, modeled after their promotional character art:|
Amy on the 2P versus character select screen.
Blaze in place of Silver on the character select screen.