Cheats I know work

The Energy Cheat
Now I confirm this cheat is a 'killing' cheat or a cheat that destroys your digimon by making your digimon ill or slluggish without you knowing it. I've warned you don't try this cheat cause when i ask my japanese friend what is that four exclaimation it's just mean like i've told you.

Teddymon cheat
There is a way to get a TeddyMon very quickly! Using the tab that came with your Digmon or something simular stick it in the gap in your Digimon. Press button C at a constant rate and about 2 seconds after the screen has faded away take the tab out. You should see an egg and suddenly a Teddymon will appear out of nowhere. But before he can fight all his hearts need to be full. But this should stop after two days. I have heard you can get a Metal-GreyMon by pressing A or the Mamemon by pressing B.
Reasons it might not work: Sometimes if your Digimon is old it won't work. Also if you have tried it loads of times it won't work either because you can ruin the circuits. I have reports that it is to do with the letter on the back of the Digimon, some letters don't work

Wake mistake
If you wake your Digimon by accident you can put him back to
sleep by pressing C then A then C quickly after that. If you do it right it should go back to sleep. Alternatively you could put the time to the current hour but the minutes to 59. This is because Digimons always go back to sleep every hour.
Reasons it might not work: Because you don't press the
buttons quick enough. The hour one will always work though.

Full hearts
A rather silly cheat:- When you Digmon is a Botamon, fill up all his hearts and then keep scrolling through the stats screen. The hearts won't go down. I'm sure it would be quicker and less work for your fingers to just do it normally!
Reason it might not work: It does, honest.

Quick Morph
If your Digmon is a Koromon, you can make it a Agumon the next day by feeding it until it won't have any more and then training him to his minimum weight. Everytime a hungry heart goes down do the same. It may be hard work but it will get you a rookie the next day.
Reason it might not work: You left it too long you nasty
person.

When you are fighting press AAABBBAA and your Digimon is sure to win, even if the other one does as well, . I have also heard other versions as well. Keep your finger on B before you fight, and there is also another one saying that if you train him twice between each fight he won't die.
Reasons it might not work: To be honest I haven't tried these
yet. But I have had loads of e-mails saying they do work. Now you can be invincible in fights!

Computermon
Now you can get an eating. sleeping etc, etc, etc.... but not fighting computer! If you use the Twins code ( when your teddymon dies you press c ten times while holding down b then reset it ) then with a bit of luck you could get a computermon! WAH HEY!
Reasons it might not work: See insta-teddymon

Cheats which might work
Flaming Teddymon
Well here is the Flaming teddymon cheat, I personally don't think that this one is true because the code looks made up. It was sent to me by the same people as below. Here's what you have to do: When your teddymon dies reset it and press a 200 times b100 times and c 25 times. I'm sure this is a load of rubbish but never mind.

Secret Character
I've been told there is a 2 headed dragon, this is probably rubbish. Well they say you put the tab in press (in this order)A twice, B twice, C twice, a once, b once, then you yank the tab out. I'm betting this doesn't work, but its worth a try.

Can your digimon be invincible?
Many of you may have heard the sad slow tune your Digimon
plays when it dies. Well, me and a bunch of friends have discovered what may be a new cheat (or bug). It could be possible that your Digimon can only die in a fight if you have the sound turned on. So far, each time mine, or one of my 4 other friends Digimons have died the sound has always been turned on and that terrible tune has been played. So remember: WHEN FIGHTING LEAVE THE SOUND OFF!

It's funny how all the cheats revolve around Teddymons isn't it? Well here's another one: I've received several E-mails from people saying you can get a skull shooting Teddymon. Here's apparently what you have to do: Reset your Teddymon at 100 percent victories and when he has all his hearts full and then press abbabbabbac.