Go to the Underworld Coliseum and defeat ALL the enemies to win 'The Goddess of Fate Cup' and you will then receive the Fatal Crest Keyblade.

Complete the following Gummi missions with an 'S' rank to unlock the corresponding special models of Gummi ships.

Unlock Mushroom Model:
Complete mission 1 - Assault of the Dreadnought with an S-Rank.

Unlock Cactuar:
Complete mission 2 - Broken Highway with an S-Rank.

Unlock Cait Sith:
Complete mission 2 - Sunlight Storm with an S-Rank.

Unlock Chocobo:
Complete mission 2 - Ancient Highway with an S-Rank.

Unlock Moogle:
Complete mission 2 - Splash Island with an S-Rank.

Unlock PuPu:
Complete mission 2 - Stardust Sweep with an S-Rank.

Unlock Tonberry:
Complete mission 2 - Phantom Storm with an S-Rank.

Unlock Mandragora:
Complete mission 2 - Floating Island with an S-Rank.

Unlock Kingdom Model:
Complete mission 2 - Asteroid Sweep with an S-Rank.

Unlock Highwind Model:
Complete mission 2 - Asteroid Sweep with an S-Rank.

Unlock Fenrir:
Complete mission 2 - Assault of the Dreadnought with an S-Rank.

Unlock Secret:
Complete mission 3 - Assault of the Dreadnought with an S-Rank.

Unlock Follow the Wind:
Defeat Barbossa at Port Royal.

Unlock Guardian Soul:
Defeat Hades in the 'Underworld' section of Olympus Coliseum.

Unlock Hero's Crest:
Defeat the Hydra at Olympus Coliseum.

Unlock Hidden Dragon:
Defeat Shan-Yu in The Land of Dragons.

Unlock Holy Pumpkin:
Defeat the Test Subject in Halloween Town.

Unlock Monochrome:
Defeat Pete at Timeless River.

Unlock Oblivion:
Defeat Xigbar in 'The World that Never Was'.

Unlock Photon Debugger:
Complete the Space Paranoids.

Unlock Rumbling Rose:
Talk to Beast after returning to Beast's Castle.

Unlock Sleeping Lion:
Go to Ansem's study in Hollow Bastion.

Unlock Fenrir:
Defeat Sephiroth the optional boss at Hollow Bastion.

Unlock Star Seeker:
Get Valor Form at The Mysterious Tower.

Unlock Wisher's Lamp:
Defeat Jafar in Agrabah.

Unlock Gullwing:
Talk to Yuna after Defeating Hades in the 'Underworld' section.

Unlock Sweet Memory:
Complete the 'Spooky Cave' Mini-Game in the Hundred-Acre Wood.

Unlock Ultima Weapon:
In Twilight Town get the Ultima Recipe in the basement of the mansion and then you can use the Moogle Shops to synthesize the keychain.

Unlock Oathkeeper:
Complete Sora's first visit to Twilight Town.

Unlock Wonders of the Abyss:
Complete Chapter 4 of Atlantica.

Unlock Secret Ending:
Complete ALL the worlds and Jiminy's Journal if you're in 'Standard' mode or complete ALL of the worlds if you're in 'Proud' mode.

Unlock Chicken Little:
Pick it up in the 100 Acre Wood world and it becomes available after the second cutscene.

Unlock Genie:
Defeat the Volcano and Blizzard Lord.

Unlock Peter Pan:
It is in the ship graveyard after the second visit to Port Royal.

Unlock Stitch:
When you acquire Master Form you'll find it in the hallway to the computer room in Hollow Bastion.

Unlock Berserk Mode:
Get a Metal Level of Level 30.

Unlock Bond of Flames:
Finish the fight with Axel in Twilight Town.

Unloc Secret Movie on Proud Mode:
Seal ALL Keyholes.

Unlock Hades Paradox Cup:
Max out ALL 4 drive forms and summons to level 7.

Unlock Goddess of Fate Cup:
Win the previous cups and win the first fight with Xemnas.

Unlock Titan Cup:
Complete the Olympus Coliseum for the second time.

Unlock Pain and Panic Cup
Complete Disney Castle for the first time.

Unloc Paradox Cups - Titan Cup:
Your Summon level should be at Lv. 5 and have the Paradox: Cup Pain and Panic unlocked.

Unlock Paradox Cups - Cerberus Cup:
Your Form levels must be at Lv. 5, except Final Form and You must also unlock Paradox Cup: Pain and Panic.

Unlock Torn Page 1:
Find it in the Disney Castle's Library.

Unlock Torn Page 2:
Find it in 'The Pride Lands' at the Oasis.

Unlock Torn Page 3:
Find it in the Hallow Bastion at the Crystal Fissure.

Unlock Torn Page 4:
Find it at 'The Land of the Dragons' in the Throne Room.

Unlock Torn Page 5:
Find it in Agrabah at the Tower.

Unlock Gummi Ship Level 2:
Get through Level 1 with S, A or B Ranks.

Unloc Gummi Ship Level 3:
Get through Level 1 and 2 with S, A or B Ranks.

Unlock Special Models:
Get S Rank in a Gummi ship mission.

Stitch:
At Hollow Bastion in the hallway to the computer room when you have Master Form.

Peter Pan:
In the ship grevayard in the second visit to Port Royal.

Chicken Little:
In the 100 Acre Wood after the world's second cutscene.

Genie:
Defeat Volcano Lord and Blizzard Lord.

You will recieve Keychains at various stages throughout the game which will allow you to give the Keyblade new powers and forms.

Bond of Flames:
In Twilight Town complete the fight with Axel.

Circle of Life:
At 'The Pride Lands'speak to Simba after arriving.

Fenrir:
At Hollow Bastion defeat Sephiroth (the optional boss).

Follow the Wind:
At Port Royal defeat Barbossa.

Guardian Soul:
In the 'Underworld' section of Olympus Coliseum defeat Hades.

Heros Crest:
At Olympus Coliseum defeat the Hydra.

Hidden Dragon:
In 'The Land of Dragons' defeat Shan-Yu.

Holy Pumpkin:
In Halloween Town defeat the Test Subject.

Monochrome:
At 'Timeless River' defeat Pete.

Oathkeeper:
Complete Sora's first visit to Twilight Town.

Oblivion:
In 'The World that Never Was' defeat Xigbar.

Photon Debugger:
Complete Space Paranoids.

Rumbling Rose:
After returning to Beast's Castle speak to Beast.

Sleeping Lion:
In Hollow Bastion go to Ansem's study.

Star Seeker:
At 'The Mysterious Tower' get Valor Form.

Sweet Memory:
In The Hundred-Acre Wood complete the 'Spooky Cave' Mini-Game.

Ultima Weapon:
In the basement of the mansion in Twilight Town get the Ultima Recipe and then use the Moogle Shops to synthesize the keychain.

Wisher's Lamp:
In Agrabah defeat Jafar.

Wonders of the Abyss:
Complete Chapter 4 of Atlantica.