In-game reset:-  Hold B + X press Start for about two seconds during game play. 

Teleport to main entrance:-  This trick requires a Game Boy Advance. Look at most large mirrors in the house. On the Game Boy Advance, press A while facing the mirror in the first person view to return to the main entrance.

New mansion:-  Successfully complete the game and save. Another option will be unlocked, allowing the game to be played again with various differences.

Gallery mode:-  Successfully complete the game to unlock everything in the gallery.

Finding Boos - You can capture the fifty Boos that were let go at the start of the game to get a large diamond. To do this, use the Game Boy Horror in Boo sensor mode. Boos tend to hide in rooms with lights. Search all locations within such rooms. A blue Boo sensor light indicates that there is no Boo present. A yellow Boo sensor light indicates that a Boo, Booball, or Bomb is near. A red Boo sensor light indicates you are directly next to a Boo, Booball, or Bomb. Get the Boo sensor to be red, then turn on the vacuum or press A to examine the target object. If Booball appears, leave it alone to send it at a wall. Run away if a bomb appears.

Diamond from plant - Go to the outside section and find the seen to the right of the dog house, towards the graveyard. It can be found under Toad's balcony. Get the Water Element ability and water the seed. A plant will appear. Press A on the Game Boy Horror while examining the dog house to enter it.. Defeat the Boss that is inside, then water the plant again. Continue playing the game, then water the plant again after defeating the next Boss. The plant will flower and give you a diamond. If you do not water the plant after each Boss battle, it will die. 

Change vacuum power - There are three different medals you can collect to change the powers of the Poltergeist 3000 vacuum cleaner. They are the Fire, Ice, and Water medals. When you collect the Fire Medal, you can suck up ghosts that have a ring of fire around the health hearts. Also, you can press L to spray fire from your vacuum to light candles and hit ghosts with a ice health meter. When you collect the Water Medal, you can extinguish flames that are too powerful for your vacuum to put out. Also, you can press L to spray water.

Vacuum Ghosts easier - If you can barely catch a ghost while vacuuming, or just want a faster way to do so, quickly rotate the C-Stick. This is easier for those who do not have too great of a time holding the C-Stick in the opposite direction of the ghost, as each rotation will land at least one heart off the ghosts.

Extra hearts and money - Use your vacuum to clean all lamps, chandeliers, and vases. Most of them will contain either hearts and money. 

Successfully complete the game and save. Go to the lab. Professor E. Gadds will ask where you want to go. Select the hidden mansion to play the game again with various differences.. 

Treasure rooms:-  Go to the southwest corner of the on the mansion's first floor. Vacuum the butler that carries a candle. Look at the room with the Game Boy Horror to find a mouse hole. Press A to examine the mouse hole and enter a hidden treasure room.

Take the elevator in the toy chamber up to get on the chimney in the mansion's roof. Fall off to land in a hidden treasure room. 

After you defeat the three clock soldiers, the Shyguys, and the Ice Element ghost, pick up the key that is in the top of the left ladder tower. Do not go back downstairs after you get it. Instead, go to the top right ladder tower with the hole at the top. Walk the plank that is above it and drop down. You will learn that it is really a chimney in the room where the door is boarded up. This is the only way to get into this location, which is a treasure room. The first treasure chest you open will contain a ghost. There are not that many, and you do not need a special element to defeat them. Defeat the ghost and open all the treasure chests. You will also get a key to another room. Exit through the mirror transport.

Defeating Boolousus:-  When you get a chance, try to locate one of the frozen unicorns at one of the end of the balcony. While he's chasing you, just run circles around the unicorn. He will eventually run into the spike and pop on his own. Be careful -- once the Boos are separated, you have to watch your back. They will run up behind you if you are not looking at them.

Defeating Chauncey:-  After you defeat the Neville and Lydia, you get to Chauncey (the baby). You have to defeat him two times. The first time, you have to pick up the ball with the Poultergust 3000, aim, and press L to fire. Hit her and she will blab about her owee. You become small and she will be very big. She will throw rocking horses and balls. When all the balls are done bouncing, one will be stationary. Pick it up, aim, and shoot it at her. 

Defeating Lydia:-  Use the following trick to capture Lydia. After you defeat the Neville, he will give you a key. Go to the room at the end of the hall. Enter and a girl ghost will be there, setting her hair. Go to the window go in front of the curtain to the right. Stand facing to the right then vacuum with the Poultergust 3000. It will move to the right and the ghost will walk to the window saying "Oh what a draft". Use this chance to vacuum her up.

Defeating: Mr. Luggs:-  Use our Fire element to light the two candles. Suck up his food with the vacuum. Ghosts will appear and serve him -- vacuum them up. When the food is gone, he will shoot fireballs at you. Dodge them and when he starts panting, vacuum him up. 

Defeating Neville:-  To capture Neville, go over to the bookcase and vacuum with the Poultergust 3000. Books will fly out and he will go over to fix them. Use this opportunity to flash the light and vacuum him in. You still have to vacuum in 100 heart power. If you fail the first time, he will still not regain health. Repeat this a few times to vacuum him in.

Finding Henry And Orville:-  After the twins tell you to hide and you reenter, vacuum the boxes. If the box shakes, open it. 

King Boo:-  When you finally make it to King Boo, you will have to walk very close to start him talking. Instead, go directly to the right. You will see two vase-like objects with purple flames coming out of them. Hit them (to check inside) to find a gold bat in one and a lot of coins in the other.