Unlock Egg Vaccum:
Beat normal story (the middle 3 stages on the map).
Unlock Samarui Blade:
Beat dark story (the top 3 stages on the map).
Unlock Heal Cannon:
Beat hero story (the bottom 3 stages on map).
Unlock Satelite Laser:
Beat semi dark story (the top middle 3 stages on map).
Unlock Omochao Gun:
Beat semi hero story (the bottom middle 3 stages on map).
2 Player Co-op mode:
On Story Mode, have your selected story mission as Hero and insert a controller into the P2 socket. The P2 controller should beable to move the Hero Character. These Characters include: Sonic, Tails, Knuckles, Maria etc. This is very useful against Bosses. Note: they cannot carry weapons.
(supplied by: james.masterson1)