Secrets found in the Gameboy Color version of Harry Potter and the Chamber of Secrets.
 Duelling Club
|1st Year||Rowena Ravenclaw card|
|2nd Year||Honouria Nutcomb card|
|3rd Year||Replenish Magic or Create Potion Combo|
|4th Year||Steel Mesh Gloves|
|5th Year||Dragon Skin Boots|
|6th Year||Rabbit's Foot|
|7th Year||Duelling Trophy|
The Duelling Club is available after Gilderoy Lockhart tells you about it and will stay available until your duel with Malfoy. After duelling Malfoy, it is impossible to battle the students until you finish the game. Seven students must be defeated before you can call yourself the champion. In the table next to this text you can see the rewards you earn after defeating each student.
 Fake Wall in Borgin and Burkes
Borgin and Burkes is the store you get warped to after using Floo Powder in an attempt to get to Diagon Alley. As you arrive, you'll notice an unreachable room at your left. Wait for the dialogue to finish and then walk toward the wall that separates you from the room and keep going until you walk through it. Follow the path until the end. Press A in front of the left bookcase to obtain Famous Witches and Wizards Card #20, Merwyn the Malicious.
 Fake Wall in Gambol and Japes
Gambol and Japes is a building located in Diagon Alley, next to the book shop, where you cannot buy anything. Yet, if you go to its back, you'll notice an unreachable room at your left. In order to reach this room, simply walk toward the wall that separates you from the room and keep going until you walk through it. This room contains two chests. The left one contains Famous Witches and Wizards Card #44, Perpetua Fancourt, and the one at right Card Combination #1, Alter Enemy.
 Ghoul in Ron's House
A Ghoul lives in Ron's attic. Talk to this Ghoul and he'll give you a strange hint about chains. Go to Ron's kitchen and retrieve the Ghoul's chains by pressing A in front of the green oven. Now, return to the Ghoul, talk to him and it'll give you Famous Witches and Wizards Card #60, Cliodne.
 Learning Skurge
After Mrs. Norris gets petrified, go to Filch's office (Ground floor, second room at left) and press A while next to the book on his desk and you will learn Skurge, a spell effective against ghostly opponents. Next, Filch will come in and tell you to get out of his office. Go out, back in and talk to Filch twice and you'll receive the Leather Gloves. Once equipped, your defence will raise 16 points, and your agility 8.
 Magic Storybook Retrieval
This Side-Quest starts once you talk to Katie Bell, who asks you to do her a favor, which is to retrieve her Magic Storybook. It will end in you learning a new spell, Petrificus Totalus.
 Step 1
Go to the hospital and talk to Katie. She will ask you to do her a favor. Harry accepts her request, which is to retrieve Katie's Magic Storybook. According to Katie, the book was last seen in the Gryffindor common room.
 Step 2
Go to the Gryffindor common room and talk to the student in there. Harry asks him if he's seen Katie's Magic Storybook somewhere. The guy tells you about seeing Ginny with it, and Harry will thank him.
 Step 3
Next, head over to the third floor. Ginny is somewhere at the bottom of the area. Talk to her and Harry will tell her Katie is looking for the Magic Storybook she has. Ginny says she doesn't know the end of the story yet, and will only give it back if you give her a picture of yourself.
 Step 4
Go to the fifth floor and talk to Colin, who is located around the three red couches. Harry will ask Colin to take his picture. Colin excitedly does so, and after it's done, he will give it to you.
 Step 5
Go back to Ginny and give her your picture. She will tell you it's lovely and will return the Magic Storybook to you.
 Step 6
With the Magic Storybook back in your possession, return to Katie and give it to her. She will thank you for it and will teach you about Petrificus Totalus, a spell which is used to paralyse your enemies for a short period of time. With this, the side-quest has been completed.
 Pet Shop's Back
The Pet Shop is a shop in Diagon Alley which is located between the Healing Shop and Gambol and Japes. Talk to the owner, a girl behind a desk which you'll see right when you enter the shop, and she'll tell you the back of her shop's filled with purple toads, and asks you to clear it. Follow the path that leads to behind her and you'll see a couple of purple toads hopping around. Press A while next to either of the five, and you'll have to battle it, in which case you'll see (if you cast Informous on it) that the purple toads are actually Bullfrogs. After defeating all 5 of them, head back to the shop owner and she will give you Famous Witches and Wizards Card #21. Morgan le Fay.
 Replaying the game
Once you've defeated the Basilisk and thus completed the game, wait for the credits to finish and you'll start the game all over again, with the same level and stats you had while finishing the game and all Folio Magi, Triplicus and Bruti entries. Yet, all your items, equipment and spells will be gone.
There are two shortcuts in Hogwarts School of Witchcraft and Wizardry.
- Press A while in front of the statue next to the Girls' restroom on the First Floor to warp to the mirror next to the Hospital Wing on the Fourth Floor. This also works the other way around.
- Press A while in front of the goblin picture in a narrow path in the Hogwarts Dungeon to warp to the Sphinx statue in the middle of the Sixth Floor. This also works the other way around.
 Trading Sequence
The Gameboy Color version of Harry Potter and the Chamber of Secrets also has a trading sequence. Within 9 steps, 40 sickles will turn into a Dragon Skin Cloak, worth an amazing 15.000 Sickles.
 Step 1
When you're in Diagon Alley, go to Quality Quidditch Supplies (top, second building from left) and walk toward the shopkeeper. Ron will tell you about how much he wants a Chudley Cannons Jersey. Talk to the shopkeeper and purchase the Chudley Cannons Jersey for 40 sickles. Ron will thank you for buying it and you'll receive a Football Card.
 Step 2
Still in Diagon Alley, go to the Trading Card Shop (top, third building from left) and talk to the guy in front of the shopkeeper. He will tell you about how he likes collecting Football Cards. Harry will give him Ron's Football Card, and the guy gratefully trades it for his Misprinted Wendolyn Card.
 Step 3
If you didn't do what was said above, and therefore don't have the Misprinted Wendolyn Card, you won't be able to continue the Trading Sequence, as you will now be at Hogwarts School of Witchcraft and Wizardry. If you do have it, head to the 6th floor and walk into the room below the Writing Supplies Room. Immediately you'll notice a painting. Talk to this painting and it will tell you she likes your Misprinted Wendolyn Card (as this IS Wendolyn the Weird). Give it to her to receive a Baby Spider.
 Step 4
With the Baby Spider, go to Hagrid's Hut and talk to Hagrid. He will tell you he likes your Baby Spider, and you will give your Baby Spider in order to receive a Spiked Collar.
 Step 5
Now that you possess the Spiked Collar, head towards Filch's office (Ground Floor, second room at left) and talk to Filch. He will give you a Photo of Lockhart in exchange for your Spiked Collar.
 Step 6
A girl is wandering around at the third or fifth floor. Talk to her and she will tell you she likes Lockhart. Give her the Photo of Lockhart and she will give you a Torch.
 Step 7
With the Torch, head over to the Muggle Studies Class (Fifth floor, northwest corner) and talk to the guy in there. Knowing you're in a Muggle Studies Class and the Torch is used by Muggles, the guy will be interested in it. Give it to him to receive an Harmonica.
 Step 8
Next, head toward Music Class (Fifth floor, northeast corner) and talk to the student in there. As this is Music Class, the Harmonica will fit perfectly. The student will give you a Magic Whistle in exchange for your Harmonica.
 Step 9
Go to History of Magic Class and talk to Professor Binns, who is currently asleep. Talk to him and he'll wake up, telling you he's interested in your Magic Whistle. Because he frequently falls asleep during class, the Magic Whistle will be quite helpful for him. In exchange for your Magic Whistle, professor Binns gives you a Dragonskin Cloak. Once equipped, the Dragon Skin Cloak will give you 50 more Defence Points, 3 more Agility points and 20 more Magic Defence points. Also, the Dragon Skin Cloak is worth 15.000 Sickles. With this, the Trading Sequence has been completed.