From Sonic Retro
After beating up Whisker and his lieutenant Johnny in the boss of Pirates' Island, Sonic, Tails, and Blaze seem tantalizingly close to recovering the Jeweled Scepter. Once again though, Whisker escapes capture, darting away from Pirates' Island - and capturing the stowaway Marine while he's at it. On the deck of a distinctly modern-looking warship, the Captain climbs into the Ghost Titan, a levitating humanoid mecha, and engages in his final battle.
Like the rest of the bosses in Sonic Rush Adventure, the Ghost Titan is fought in a pseudo-3D arena. Sonic or Blaze is confined to the ship's deck on the DS' bottom screen, while the robot floats high above on the top screen (a familiar setup from the Ghost Condor). Whisker unleashes a variety of brutal attacks on the screen below: slow-moving missile barrages, shoulder-mounted laser blasts, hit-and-run strikes with the Titan's detachable arms, and even docking with the warship to punch the player into oblivion. Meanwhile, the turrets at the left and right of the screen strafe the deck with explosions.
In order to damage the Titan, the player must draw its attacks to the blue shields which surround the deck-mounted turrets. Once they take enough hits, the shields dissipate (You can also attack it regularly if you're willing to lose your rings) - spin jump the turrets to knock out their barrels, then jump inside to gain control of it yourself. Now the player can be fired up to the top screen like a cannonball, striking the Titan right in the face.
When the Titan's health bar is reduced to nothing, it crashes down to the bottom screen and begins a final, overloaded attack. Rays of pink energy spew out on either side and start to consume the whole ship. Keep your nerve and stand directly under the machine's control gem. Just before the entire screen would go white, the Titan descends far enough for you to deliver the final blow to its head.
In the subsequent cutscene, Sonic and Blaze outrun the explosion that destroys the ship. Viewing the burning wreckage from afar on the hull of the Deep Typhoon, they scold Marine for going after the pirates on her own, but the raccoon has some good news; she recovered the Jeweled Scepter! With Captain Whisker defeated and the treasure reclaimed, the heroes head home towards Southern Island.