This is focusing on the GameCube version of Animal Crossing. Now that that's out of the way let's get started!
There are 3 main ways of cheating in Animal Crossing and they all do different things.
Time Traveling
Passwords
Action Replay
First we'll be taking a look at Time Traveling since this is the most common form of cheating. Time Traveling is
changing the time on the internal GameCube clock or in-game time. You would want to do this if:
You just paid off your house and don't want to wait for it to expand
You planted a money tree and don't want to wait for it to grow
You buried a shovel and want the Golden Shovel NOW.
Now we'll take a look at passwords. Passwords are strings of letters, numbers and symbols that tell the game to give an item to someone. Here is an example:
OmxBS5@5%OgB9L
CK36SFRXZJDwr2
Normally you would get a password from a friend that would only work with your villager name and town name, But Animal Crossing has a thing called Universal Passwords. Universal Passwords do what they sound like, They give an item to someone regardless of villager name or town name. These were mainly given away with Nintendo Power but you can find them online at sites like this one: https://www.ign.com/wikis/animal-crossing/GCN_Cheats . There are also Password generators that will give you any item you want.
Finally, we're taking a look at Action Replay. Action Replay modifies a game to do some crazy stuff. It isn't just for Animal Crossing either. The Action Replay disc comes with cheats for almost every game. If you're gonna use Action Replay for Animal Crossing you want to make sure to get one that allows you to input your own cheats. Here is an example of an Action Replay cheat code:
KACQ-Y14W-28PPX
7Y9B-5XMK-9A2XQ
GPG1-G8VJ-XK46C
08KK-BVZ6-1UTJF
Action Replay can do stuff like giving you infinite Bells, Items and lots of other stuff. If you're using a USB Loader for Wii like USB Loader GX you're gonna have to decrypt that code(the example code would look like this:
0152156F 08000000
05266488 1DE01DF0
0526648C 1DC41DEC
03266490 00001DE4),
Convert it to a WiiRD code(the example code would look like this:
0152156F 00000000
05266488 1DE01DF0
0526648C 1DC41DEC
03266490 00001DE4),
and finally, Convert it to an Ocarina code(the example code would look like this:
0152156F 00000000
05266488 1DE01DF0
0526648C 1DC41DEC
03266490 00001DE4).
That's really all there is to it. Of course this takes some fun away from it but if you just want a ton of Bells to mess around with it's a great way to get more entertainment out of this great game.