How To Unlock Party Members
First you need to go to sorcere's chamber and deafeat enemy's second use all kind of dlink and get a star and go to yen sid's office and you will see a treasure open it and it will say "you have unlock party members" you can cuztomize them in the main menu and you can change them in the save point they can go to all world's you go.
Rapid Experience Gain
This area is located in "Radient Garden", in the area where you fought the giant armor. For this to work you must have the following abilities: Once more ( or second chance), and experience chance. If you have any "prize" abilities or HP boosts, turn them off. You should have your command deck full of mega flares. Run to the middle of the area, then run back to the edge of the glass. Cast mega flare twice. Then exit and repeat for however long you want.
How To Get Ragnarok
Ragnarok is used in Kingdom hearts and Kingdom Hearts 2 as an abilitie , but on here it is a finish move. Press start and go to the command board and play on the Land of Departure board and play threw the game and win and you can choose between two prizes blizzard or ragnarok.
You will start off with this keyblade if you choose Ventus (or Ven) at the start of the game.