Pikmin

Challenge mode option:
Save the game at any point to unlock a "Challenge Mode" option at the main menu.
Select that option to replay previously completed sections in a time attack type scenario.
Collect as many Pikmin as possible before nightfall.

Hint: Fireworks:
Press Down to round up four Pikmin to carry you back to your base camp.
A short fireworks display appear.
This also eventually happens if you stand idle.

Hint: Get more Pikmin:
Note the color of the pellets when you have the Pikmin carry them to their "Onions." The destination that Pikmin will carry objects to depends on the members of the group.
If there are more blue Pikmin than red Pikmin in the group, they will bring it to the blue hive.
When the same color pellet is brought to the corresponding hive color it will produce more new Pikmin than if the colors does not match.

Hint: Getting various colored Pikmin:
You can get the Red Pikmin when you start the game (Impact Site).
You can get Yellow Pikmin when you get to the next area (Forest Of Hope).
You can get the Blue Pikmin in the third area (Forest Navel).

Hint: Bombs:
When you are trying to blow up walls with your Yellow Pikmin and have bombs remaining after the task is completed, keep them.
They are very useful for killing enemies.
Keep the Pikmin with the bombs away from the group.
If a bomb explodes, your entire group may die.
To use the Pikmin with the leftover bombs, simply throw them at the target and call them back.
This will either injure or kill the enemy.
If the enemy is not dead just call your group and finish it off.

Hint: Defeating the Armed Beetle:
To defeat the Armed Beetle in the Distant Spring, wait until it is about to take a breath.
It does this immediately before spitting out a rock.
Then, throw a Pikmin at it.
If you aimed correctly, the Pikmin should get sucked in and the beetle will open its shell, exposing its vulnerable body.
Then, just have your Pikmin attack it.

Hint: Defeating Burrowing Snagret:
Start attacking it until it goes underground.
Have your Pikmin stand above where it burrowed.
When it comes up, the Pikmin will be able to attack its head.
This inflicts more damage.

Hint: Defeating Puffstool:
To defeat the Puffstool in the Forest Navel easily, beat him by yourself by pressing A near him.
He does not do any damage -- just take the time to defeat him instead of losing a lot and Pikmin (and health since the Pikmin attack you).

Although it is true that Puffstool's spores do not damage you (because of your spacesuit), it is rather inefficient to damage him yourself.
An army of red Pikmin are useful in battle, but you have to do two things.
First, while Puff is standing, have them attack its feet.
It will fall over on its head, wiggling around helplessly.
Some will hang on to his feet, while the others will fall off.
Instead of ordering them to attack again, throw your red Pikmin on top.
His underside is easily damaged more than his head.
However, it is very unlikely you will kill him before he flips over and tries to spray your Pikmin, turning them into Toadmin that will attack you.
The easiest solution is to press B to recall them before he flips over, which is about fifteen seconds.
Bring every one of them away from PuffStool and wait for it to spray.
After the spores have dissipated, attack his feet and resume.
It should only take two times to knock him out and get your part, as well as a mushroom cap to feed your Onions with.

Hint: Distant Springs: Wetland frogs:
When you have to build the bridge from both sides to get the part for your spaceship, you may lose a lot of Pikmin from the frog that is there.
Leave your Pikmin in their "Onions" when you begin and go over to kill the frog.
It will be easier and safer for your Pikmin to build their bridge.

Hint: Learning about enemies:
Start a new day, then take out a few Pikmin.
Take them directly to the enemy, and start fighting.
If you encounter anything on your way to the enemy, this trick will not work.
As soon as you start the fight, pause game play and select "Go to Sunset." If there is nothing else special about this day, Olimar's log entry will describe the enemy.
After the log entry, at the title screen, choose "Don't Save" and then "Continue From Last Save" to avoid wasting a day.
This does not always work, for example if this day was also your first day in a new area, you discovered a new color of Pikmin, or something similar.

Hint: Advanced throwing technique:
This trick is very helpful in fighting Pearly Clamclamps and Emperor Bulblax.
If you want to throw Pikmin very rapidly, to do a lot of damage, press A rapidly while also using the C-stick to make the Pikmin swarm around Olimar.
There will always be a Pikmin handy for Olimar to throw every time you press A.

Hint: Save Pikmin from drowning:
Repeatedly blow your whistle at Pikmin to drag them up onto land.

To keep your Red or Yellow Pikmin from drowning, have Blue Pikmin by the border.
Do not have them selected.
If a Red or Yellow Pikmin falls in the water near your Blue Pikmin, they will go to the Pikmin and throw them on land.

Hint: Get carried to Onion:
Press Down and Olimar will lay down.
If he has any Pikmin with him, five of them will carry him to the Onion and the rest will stay behind.

Hint: Captain's logs:
To see the pages where Olimar had written his discoveries, press Y on the area selection screen.