Paper Mario: The Thousand-Year Door Cheats

Style
Directly after a hammer attack, or at the highest point after a jump attack, tap A again and Mario will do a stylish trick earning him more star points. This works for his allies as well. Tap A directly after doing Koops shell throw and he will spin on his back earning more style.

Turn into NES Mario
Just like in the first Paper Mario, there is an easter egg to revert Mario from paper to 8-bit sprite. Only this time it works on your partners too! In the X-Naut Base in Chapter Seven. Find the room with the swinging grate on Sublevel 2. Stand under it and use your Ultra Jump to jump up into the air vent. Press R and slide through the grate on the far right. You'll land in the changing room where Peach disguised herself, inside one of the stalls. When you pull back the curtain, you and your partner will be a sprite. This change does not affect game play and will wear off when you leave the room.

Yoshi's color
When naming a game, use a color for your name and Yoshi will be that color.

Extra Clothes
Luigi clothes - From where you get the sixth crystal star, do a spring jump up to a pole on the left side. Do another spring jump to reach a ledge with the Luigi Emblem.
Waluigi clothes - Equip both the Luigi Emblem and the Wario Emblem at the same time.
Wario clothes - Go to the central area of Rougeport with 360 Coins. There should be a merchant with a large mustache. He sells something called a Wario Emblem from time to time. It is a badge that requires no badge points to wear.

Rewards available in the Pit of 100 Trials
For every 10 levels you complete in the Pit of 100 Trials, you'll earn a new badge or other item:

Bump Attack Badge - Complete levels 71-80
Double Dip Badge - Complete levels 51-60
Double Dip P Badge - Complete levels 61-70
Fire Drive Badge - Complete levels 11-20
Lucky Day Badge - Complete levels 81-90
Pity Flower Badge - Complete levels 31-40
Return Postage Badge - Complete levels 91-100
Strange Sack (doubles inventory space) - Complete levels 41-50
Sleepy Stomp Badge - Complete levels 1-10
Zap Tap Badge - Complete levels 21-30

Super Mario World music
When you get an important e-mail (ie; the e-mails from Princess Peach), wait a couple of seconds and you will hear music from Super Mario World.

Whack a Mole
In chapter 5 on Keelhaul Key, walk to the northwest of the camp. Talk to the mole and hit him with your hammer he will leave behind a bump, get the bump. You can leave the area and go back there again to repeat this. You can sell the bump at the store for 50 bucks.

Free Tattle
Go to Profesor Frankly's office and press the big green button (A) at his garbage and info about a random enemy and is transferred to your tattle log.