All Working Harry Potter and the Chamber of Secrets Cheats - GBA

Cheat mode
Go to the broom shed and do a task. If you win a card press [R] and a screen will appear. Press [B] to display the cheat menu.

Play as Crabb
Enable the "Cheat mode" code. In the cheat menu, go the "Select Level" option. Select Polyjuice Potion and get up to the part when you transform into Crabb. Save the game and quit. The cheat menu will appear. Use the "Select Map" option then go to Diagon Alley.

Bestiary option
Complete the five Famous Witches and Wizards cards "Creatures" in your collection. After you collected all five, there will be a new category in your menu which will give information about the creatures you will commonly see in the game.

Gemstones to open the door

Gemstone 1: In the first chest box near the slugs.
Gemstone 2: Defeat all three Fire Turtles.
Gemstone 3: In the box next to the switch that activates the crushers.

First card: Found during your Leviosa Challenge.
Second card: Secret room in portrait hall.
Third card: Room in Flitwick's office.
Fourth card: Secret room, corner of Gryffindor common room where you light torches with incendio to open a wall.
Fifth card: Bonus room in portrait hall, with male portrait.

Magical Creature cards

West Great Hall.
East Whomping Willow.
Moaning Myrtle's (Alohamora needed).
Avifors Lesson.
Portrait Room: Female Portrait.

Alohomora spell
In order to get the last spell, Alohomora, you must get all five Famous Witches And Wizards "Charms" cards in your collection.

Floo Powder
When in the leaky cauldron, go into the room by the furnace and pull the lever found in the room. Then, go out of the room. Go to the west side of the store. Pull the lever and the bookcase will open. Go inside the room and open the chest. You will obtain the Floo Powder. Take it to Ron and you will go to Hogwarts.

Girding Potions
Complete the five Famous Witches and Wizards card "Potions", and you will receive five Girding potions.

Increase your boost bar
When at the flying lessons press [A] at the start when the countdown reaches "1". Note: Timing is critical.

Defeating The Basilisk
Have the selected spell as Inciendio. This should do more damage than Flipendo. When you enter the chamber, Fawks should "take" his eyes, making him blind. When he goes in a circle, continuously cast Inciendio. Make sure he does not touch you, or you will be poisoned. Watch out when he makes rocks come down and dodge his spit. This may take awhile, but you will eventually defeat him.

Secret room in portrait hall
Go towards the end of the portrait hall. You will see a metal chain door. In order to open it, search for the lever or switch near the door by pressing [A] (Action). When it shows up, press "A "button again besides the switch to open the chain door. Enter it to find the second card from your Charms collection.