Sonic Rush Adventure
Play as Blaze
Defeat the Kraken Boss in World 3 (Coral Cave) to play as Blaze the cat.
Play as Super Sonic and Super Blaze
Collect all seven Chaos Emeralds and all seven Sol Emeralds and unlock the Magma Hurricane and Deep Core.
Defeat the Titan Boss in Big Swell. Then go to Seagull Beach on Windmill Island. Talk to the koala with the guitar to hear the music, dialogue, and sound effects. Note: This will also open additional missions.
Collect all Sol Emeralds and Chaos Emeralds to unlock
the "Deep Core" extra final Boss level.
Faster Chaos Emeralds
When you complete the game, after fighting at Big Swell, Tails will ask you to obtain material for him to power up your watercrafts. Although it is annoying going through stages, you must power up the water bike twice to get the emeralds faster. Note: This is excludes Sol emeralds. Also, Tails might ask you to power up before the game is over.
Strategy guides from GameFAQs