Pikmin 2 Cheats

Get a group of mostly Red Pikmin. Listen to them closely to hear them hum the theme song from Luigi's Mansion.

At the title screen (where it says "press Start"), press the X button to make a beetle appear. Once the insect is on the screen, you can use left and right on the C-Stick to turn it and forward to move. If you move the bug into the Pikmin that make up the logo, they will "interact" with the bug.
Press Y to make a Chappie appear. You can move it around the same way and press Z to make it eat Pikmin. To get rid of the creatures, press the L button.
Press R to make the Pikmin run around the screen and then rearrange themselves to form the word "Nintendo."

Unlock Challenge Mode:
To unlock the Challenge mode unearth the key item that is found on the fifth
floor of the Summer stage's first dungeon.
Unlock Treasure Completion Sequence:
To unlock the treasure completion sequence collect all the pieces and rescue Looie.
Unlock Shyacho:
To unlock Shyacho collect 10,000 Pocos to save Hokotate Intergalactic
Delivery then choose continue.
Unlock Cinemas and Credits:
To unlock the cinemas and credits collect 10,000 pocos.

Get 10,000 pocos

Collect 10,000 pocos to save Hokotate Intergalactic Delivery, then choose to continue.

To key to unlocking Pikmin 2's Challenge Mode(for one or two players) lies in the game's third zone -- the lake area. Once you have unlocked it, grab a group of yellow and red Pikmin as well as a handful of white Pikmin (to dig up hidden treasures along the way). No blue Pikmin needed. Fight the electric bugs and fire
emitters with the matching Pikmin and make your way to basement level 5. Fight the mechanical spider with a small group of yellow Pikmin: throw them at the spider's body, then call them back to you and move them out of the way when the spider is stomping its feet. When you have beaten the spider, a key (literally) appears. Have the Pikmin bring it back and exit the level by jumping into the geyser. The Challenge Mode will now be available for selection from the main menu.