Super Paper Mario Cheats

Game Arcade
If you go into 3-D mode while in the coffee shop in Flipside B1, you can access a gold pipe that will take you to an arcade where you can play three different arcade games using different functions of the Wii remote, winning prizes for top scores. A fourth game can be unlocked if you have a Gold Card.

Piccolo Pixl
You must first have completed Chapter 5 to be able to complete this. First, go to Merlee's house on the 2nd floor in Flopside. You have to jump over her crystal ball to talk to her, otherwise she'll just offer you charms. She will send you on a fetch mission to Merluvlee on the 2nd floor of Flipside. From there, you will have to travel to World 1-1. You're going to be using your Return Pipe quite a bit. Talk to Bestuvius at the end of the first area in 1-1. He'll send you to talk to Watchitt in Yold Town.

Use your Return Pipe then go back into the red door to get to 1-2. Continue through the area until you get to the town. The third house is Watchitt's. He will send you on your fourth fetch mission to see Merlumina. Use the Return Pipe and go back to the red door. Choose to go to 1-4 and travel through the whole chapter. At the end (past where you fought Fracktail), you'll go into a house and when you run towards the star Merlumina will appear. After a lengthy bit of text, she'll sign the autograph and you can return to Watchitt in 1-2. Then go back to 1-1 to give the "you-know-what" to Bestuvius, and then to Flipside to give the Training Machine, a Nintendo DS, to Merluvlee. Finally take the Crystal Ball from her to Merlee in Flopside and she'll give you a key.

This key can be used on the locked door in Flopside. The door is on the 1st floor through the piece of the wall that you bombed earlier. Inside you'll find Piccolo. There are only two place I have found to use him. Go to the 2nd floor of Flipside, flip to 3D and go through the gate across from the White Tower. Instead of crossing the bridge, return to 2D and go to the left of the screen. You'll see a pipe up above. Use Boomer to blast the bricks and enter it. You'll now be on the 3rd floor of Flipside. Piccolo can be used on the block with the music note, which is all the way to the right. You'll get a Merlee card. In the same place in Flopside you'll get a Nolrem card. These are the only place I've found so far to use Piccolo.