Always a Blue Shell
In the stage "Koopa Beach" the item on top of the rock is a BLUE shell every time. To get it you do NOT need a mushroom or a star but they help quite a bit. If you don't have a mushroom or a star you may get it but you will probably hit the box and fall but if you have enough speed you will grab it and be able to continually drive on to romp home for a first place.
Note: If you have a super mushroom from the last batch of items it will not have run out in time to maintain the blue shell.
Banana Trick
Hit the brakes as soon as you hit a banana peel. Hold the brakes for 1 second, then release and hit the gas. This will prevent you from skidding or losing a balloon in Battle Mode.
Drafting
If you can't pass an opponent, try drafting him. Line your kart up behind another racer. You'll see wisps of air come off your kart and you'll speed up slightly. Not much, but enough to pass whomever you're following.
Ghost Riders
You're probably familiar with the standard ghost racers (the ones you create in Time Trial mode), but did you know the course was haunted before you arrived?
To play against the official course ghosts, enter Time Trial mode and complete a track within the time shown below. After beating this time, immediately RETRY and you'll be see the message, "Now Meet the Course Ghost."
Course
Time to Beat
Mario Raceway
1'30"00
Luigi Raceway
1'52"00
Royal Raceway
2'40"00
Item Shield
You can hold a single weapon item (shells, explosive box or bananas) behind your Kart by Z. This can allow you to obtain other items or be used as a shield against attacks from behind.
Mario 64 Castle
On the Royal Raceway after the big jump there will be a yellow road to the right. If you follow it, it will bring you to the Mario 64 castle.
Mega Jump
If you're using a mushroom or a turbo boost, jump when another driver is immediately in front of you. If your timing is right, you'll sail over their head.
Mirror Mode and New Title Screen
For a new title screen and access to Mirror Mode you must win a gold cup in all 150cc events. Good luck!
Prevent Skidding
If you skid or blow up, rapidly tap the GAS button until you recover (usually 3 to 5 times.) If you see a music sign then you did the trick right.
Quick Lap On Frappe Snowland
When you start, do a U-turn and drive backwards. (Don't worry about Liukitu's REVERSE sign) Keep driving until you get to the end of a bridge. At the end, jump off the RIGHT side of the bridge and onto the snow. Keep driving, and Likitu will pick you up and place you completely on the bridge. (If you are placed back on the snow, then it didn't work.) If you executed this correctly, you will have advanced the entire lap. Repeat this trick (after crossing the finish line) and you should be able to finish the track in 45 seconds or less!
Throwing Tricks
To throw a banana forwards, hold Z while holding a banana, then press the joystick UP and release Z.
To toss a turtle shell behind you, hold Z while holding a banana, then press the joystick DOWN and release Z.
Turbo Boost
Press A as the starting light turns green. If your timing is right you'll race ahead of the other players.
Using the ¿ Boxes Usefully
I use this trick all the time to help my chance of winning in almost every mode of play. When I get a ¿ box, I wait until I see another item box one before planting mine. If I time it just right, the ¿ box I laid down will be right on top of where the original one was so if anyone goes to get it they can't tell it was a fake until they hit it!