Eat the lightbulb!
When your dog is learning a command, ex:lay down,roll over. A lightbulb icon appears in the top right corner of the screen. Click on the light bulb and record your command. If the dog accepts the command, a sketchy like lightbulb appears over their adorable little head. Grab the lightbulb with your stylus then drag it to the dogs mouth. And they will EAT THE LIGHTBULB like a treat!Note: This was found in the Japanese version. I am not sure about the North American version.

Unlock Jack Russel Terrier
While on a walk, your dog may come across an Item called the Jack Russel Book. If you visit the kennel, you can now buy the single Jack Russel Terrier

Unlock Welsh Corgi
Collect 2000 Owner Points

Unlock Pug
Collect 4000 Owner Points

Unlock Shetland
Sheepdog Collect 8000 Owner Points

Unlock Schnauzer
Collect 10000 Owner Points

Unlock Pinscher
Collect 14000 Owner Points

Unlock German Shepherd
Collect 17000 Owner Points

Unlock Japanese Style House (from Shiba Pack)
20000 Owner Points

Unlock Toy Poodle
25000 Owner Points

Balloon:
Get 300 owner points.

Jump Rope:
Get 300 owner points.

Windup Toy:
Get 10,000 owner points.

Natural Dog Food Bag:
Get 10,000 owner points.

Pull Rope:
Get 300 owner points.

Reset data:
Hold L + R + A + B + X + Y at the Nintendo logo to delete your saved data.

Miniature Schnauzer:
Get 14,000 owner points.

Pinscher:
Get 2,000 owner points. Get 14,000 owner points in the Japanese version of the game.

Pembroke Welsh Corgi:
Get 20,000 owner points. Get 2,000 owner points in the Japanese version of the game.

Pug:
Get 35,000 owner points. Get 4,000 owner points in the Japanese version of the game.

Schnauzer:
Get 14,000 owner points. Get 10,000 owner points in the Japanese version of the game.

Shetland Sheepdog:
Get 8,000 owner points in the Japanese version of the game.

Siberian Husky:
Get 4,000 owner points.

Walk without waiting 30 minutes!
To do this trick, make sure you have an Asscessory on you. Select which dog you want to walk with. While planning the route for the dog, go through as many[?] blocks as possible. Once you have done that, make your way to the park, then back to your house. When your dog starts the walk, when it gets to the park change the accessory it's wearing into something else. After the game finishes saving, turn off your Nintendo DS. When you reboot you will notice that you have obtained all the items you did in the walk, and you can walk again with the same dog without the wait. Do this for present abuse!

Dog or present?
When walking your dog, if he/she comes upon a ? mark, he/she will bark once, or twice. Most of the time, one bark means a present, two barks means another dog.

Easy way to find hidden presents
When going on a walk, watch the top screen. When the dog icon stops moving, there is a hidden present coming up shortly. Be cautious, however, as this is also true when garbage is coming up, or your pup simply stops by itself.

Get unlockable breeds easier.
Do Bark Mode with a dog in a breed that you don't have.Example: Do Bark Mode with a Shih Tzu and after you do Bark Mode with that dog, you will be able to buy the Shih Tzu breed at the kennel.NOTE: This only works the first time with each different version of the game. So you can do this trick one time with Labrador & Friends, Dachshund & Friends, and any other version of Nintendogs.

Linking:
When linking copies of Nintendogs to unlock new breeds, keep in mind two things. You can only link with another Nintendo DS system once (and unlock a new breed). The breed unlocked corresponds with your partner's current pet, and it must be a breed that you do not have in order for it to be unlocked.

RC helicopter:
Go on a walk and you may find an RC helicopter as one of the question marks. Hold A to take off, the D-Pad to maneuver, and L to change the camera view. Note: They can be sold for $200.

Agility training:
Go to the gymnasium and train your dog on the agility course. It changes with each contest you win.

Disc contest:
Get a Boxer if you want speed. Get a German Shepherd if you want it to jump high.

Blue circles on the map:
While on walks, blue circles represent places to go to the bathroom.

Longer walks:
Mark out the path on your map, ending it at the house. If your last few steps ends at the house, wait 25 minutes, then your dog can go slighter further on the next walk. Note: Make sure to water your dog after each walk.

Different colored Dogs:
While at the pound, pick a breed. You will have three choices for the dog's coloring *light, medium, and dark). If you do not see the color you like, tap "Back", then tap on the breed again until the color and/or gender that you want with the dog appears. It may take some time to actually get what you want.

Hand stand:
Teach your dog to lie down and beg. While lying down, tell it to beg and your dog should do a handstand.

Flip from back:
Teach your dog roll over and jump. Tell it to roll over then quickly have it jump. It should flip forward onto its legs, with something that resembles a Kung Fu-style move.

Getting money:
Go on a lot of walks, getting as many question marks as you can along the way. Then, go to the second hand store and sell all the items you do not want or your dog(s) do not like. Some items are less then a dollar, but the amount adds up if you keep doing this.

Losing contests:
In certain classes of contests, if you get below a certain score you will drop a class.

Walking your dog:
When walking your dog and it seems edgy, give the leash a little tug towards the way it is walking. The dog will start running. Also, if you want you can give it a tug while running upwards, it will do a jump.