Cheats for Super Mario Sunshine (GAMECUBE)

Alternate ending screen:
If you complete the game with 119 Shine Sprites or less you will get an ending screen in which el Piantissimo inspects the paintbrush. However, if you finish it with all 120 Shine Sprites, the ending screen will show all the characters in the game.

Ending bonus:
Successfully complete and save the game. You can pay 10 coins to use a boat near the clock tower where Yoshi is found to return to the Airport level at the start of the game. Additionally, you can get a Hawaiian shirt in addition to the sunglasses that the man wearing sunglasses gives Mario normally during the game.

Return to the Airport
Once you've beaten the game (and saved your game), you will be able to go back to the Airport from the very beginning. It'll cost you, though. For the price of 10 coins, a boat close to the clocktower where you find Yoshi will take you to the Airport level -- which is filled with coins and fun stuff to do. Give it a try!

Sunglasses and Hawaiian Shirt
Want to see Mario in a different outfit than his trademark blue overalls and red shirt? How about putting on some shades and slipping into a shirt that would make even Tom Selleck jealous? The shades are easy to get. Look for a man with black sunglasses in the hub world (he's at the beach, close to the fruit stands) or in most of the other levels and talk to him. When you've gotten 30 Shines, he'll give you a pair of sunglasses to wear, which will darken your screen appropriately. Note, the sunglasses will disappear the moment you step into another level or restart the game. The same guy will also give you a Hawaiian shirt -- but you've got to do some work first: finish the game. If you've saved your game after you beat the last big boss, you'll be able to get your shirt anytime you talk to this guy.

Bubba-Proof
In Gelato Beach and other levels where there are Bubbas (the big red fish that drags Mario underwater), you can keep them from doing this attack with this little trick.

Pick up a piece of fruit and start swimming with it. It will enable a glitch where they cannot drag you. This is very useful for the Red Coin Shine in Gelato Beach. Conserve Lives
To build up Mario's stock, try to quit stages when you are about to die. This would apply to stages like the racing stages (with the Islander who likes to race) and some of the mini-stages (like the Pachinko stage).
If you can restart the stage easily (and quickly), you should learn to quit when Mario is in danger of dying. This will let you have a large stock of lives to tackle stages and mini-stages that you want a lot of lives to spend on (the Dead Leaf in a Dirty Brook mini-stage comes immediately to mind).