Sonic Heroes Cheat: Metal Sheen
Hold A and Y after selecting a 2-player level to have a "metallic" skin covering over your team.

Sonic Heroes Unlockable: Super Hard Difficulty
Beat the game with 141 Emblems and all A ratings.

Sonic Heroes Unlockables: New 2P Modes

2P Action Race Unlocked from start
2P Bobsled Race Collect 80 emblems
2P Expert Race Collect 120 emblems
2P Quick Race Collect 100 emblems
2P Ring Race Collect 60 emblems
2P Special Stage Collect 40 emblems
2P Team Battle Collect 20 emblems

Sonic Heroes Unlockables: CG Threatres

Team Chaotix Cinema: Complete Team Chaotix in Story Mode
Team Dark Cinema: Complete Team Dark in Story Mode
Team Rose Cinema: Complete Team Rose in Story Mode
Team Sonic Cinema: Complete Team Sonic in Story Mode

Sonic Heroes Unlockables: Last Story
Collect all 7 Chaos Emeralds and finish all stories

Sonic Heroes Unlockable: Theme Songs

"Follow me": Finish Team Rose story mode.
"Sonic Heroes": Unlocked by default.
"Team Chatoix": Finish Team Chatoix story mode.
"This Machine": Finish Team Dark story mode.
"We Can": Finish Team Sony story mode.
"What I'm Made Of": Finish Last Story.

Sonic Heroes Hint: Japanese Voices
Change your Xbox's system language to "Japanese" and then start the game. The original Japanese voices will replace the American ones.

Sonic Heroes Hint: Team blast gauge recharge
While playing the game with either team sonic, dark, or etc. switch to fly formation then press and hold the x and y buttons at the same time. You will switch to power formation while the one who can fly will stay in the air until your gauge is power up by at least 35 percent. Do it as many times as you like