Godzilla Unleashed: Double Smash Cheats

Characters Unlockables
Anguirus: Defeat "Hedorah Terrorizes San Francisco" stage
Destoroyah: Defeat "Monster Island, The Final Battle" stage
Fire Rodan: Defeat "Biollante Attacks Paris" stage
King Ghidorah: Defeat "Mecha King Ghidorah Ravages Bangkok" stage
Gigan: Beat "Ebirah Swamps" level.
Krystalak: Unlock all other characters but Biolantte attacks Paris, then beat it and you will get Krystaslak along with Fire Rodan.

Concept art and 3D models
Any playable character: Defeat "Monster Island, The Final Battle" level with that character
Atorgon: Defeat "Atlantis Rises From The Deep" level
Baragon: Defeat "Hedorah Terrorizes San Francisco" level
Biollante: Defeat "Biollante Attacks Paris" level
Destoroyah (NPC): Defeat "Monster Island, The Final Battle" level
Ebirah: Defeat "Ebirah Swamps Tokyo" level
Hedorah: Defeat "Hedorah Terrorizes San Francisco" level
Jet Jaguar: Defeat "Orga Thrashes Sydney" level
Manda: Defeat "Atlantis Rises From The Deep" level
Mecha King Ghidorah: Defeat "Mecha King Ghidorah Ravages Bangkok" level
Mechagodzilla: Defeat "Cairo Is...Lost In Space" level
Megaguirus: Defeat "Biollante Attacks Paris" level
Moguera: Defeat "Mecha King Ghidorah Ravages Bangkok" level
Orga: Defeat "Orga Thrashes Sydney" level
SpaceGodzilla: Defeat "Monster Island, The Final Battle" level
The Sphinx: Defeat "Cairo Is...Lost In Space" level
Titanosaurus: Defeat "Ebirah Swamps Tokyo" level