Pikmin 2

Easter Egg: Title Screen Fun
At the title screen, press X to make a beetle appear. You can now use Left and Right on the C-Stick to turn it and move it. Move the bug into the Pikmin that make up the logo, to interact with each other. Press Y to make a Chappie appear. You can move it the same way as above and press Z to make it eat Pikmin. Press L to clear the bugs. Press R to make the Pikmin move around the screen and then watch as they rearrange themselves to form the word "Nintendo".
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Unlock Awakening Wood
Collect the Sphere map in Emergence Cave.
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Unlock Challenge Mode
Unlock the Lake Area (the third zone), then take a group of yellow, red and white Pikmin. Make your way to Basement Level 5, fighting the electric bugs and fire emitters with the matching Pikmin. Using a small group of yellow Pikmin, fight the mechanical spider by throwing them at the spider's body, calling them back to you when the spider is stomping its feet. A key will appear when you have beaten the spider. Have the Pikmin return with it, then exit the level by jumping into the geyser. The Challenge Mode will now be available for selection from the Main Menu.
(Thanks to xgamingguru@hotmail.com)

Unlock Cinemas and Credits
Collect 10,000 pocos.
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Unlock Louie's Dark Secret Movie
Complete all 30 Challenge Mode Arenas obtaining pink flowers (no Pikmin deaths).
(Thanks to xgamingguru@hotmail.com)

Unlock Perplexing Pool
Collect the Exploration map in the Awakening Wood.
(Thanks to xgamingguru@hotmail.com)

Unlock Pikmin 1 Theme Song
Assemble 20 of each of the 5 coloured Pikmin into a single group to hear them hum the Japanese Pikmin 1 theme song, “Ai no Uta” by Strawberry Flower.
(Thanks to xgamingguru@hotmail.com)

Unlock Treasure Completion Movie
Collect all the pieces and rescue Louie.
(Thanks to xgamingguru@hotmail.com)

Unlock Wistful Wild
Repay the 10,000 pokos of your company's debt.
(Thanks to xgamingguru@hotmail.com)