Mario Kart: Double Dash!! Cheat Codes for Gamecube

Bowser Jr.'s Kart:
Win the Special Cup in the 50cc class.

Daisy's Kart:
Win the Flower Cup in the 50cc class.

Diddy Kong's Kart:
Win the Star Cup in the 150cc class.

King Boo's Kart:
Win the Special Cup in mirror mode.

All Cup Tour:
Win the Special Cup in the 150cc class to unlock the All Cup Tour, which is a combination of all of the four default cups.

Special Cup:
Win the Star Cup in the 100cc class.

Mirror mode:
Win the All Cup Tour in the 150cc class.

Luigi's Mansion battle arena:
Win the Mushroom Cup in the 150cc class.

Tilt-A-Kart battle arena:
Win the Flower Cup in mirror mode.

Baby Luigi's Kart:
Win the Mushroom Cup in the 100cc class.

Birdo's Kart:
Win the Flower Cup in the 150cc class.

Alternate opening and ending screens:
Win the All Cup Tour in mirror mode.

All bonuses:
Will all cups with a "Gold" rank under all difficulty settings.

Unlocking new Karts in Grand Prix:
Win a Grand Prix in first place to unlock a new Kart. There is a bonus Kart in each cc class and Grand Prix that you can win (nine total).

Koopa Paratroopa's Kart:
Win the Star Cup in the 50cc class.

Luigi's Kart:
Win the Mushroom Cup in the 50cc class.

Petey Piranha's Kart:
Win the Star Cup in mirror mode.

Toadette's Kart:
Win the Mushroom Cup in mirror mode.

Toad's Kart:
Win the Special Cup in the 100cc class.

Toadsworth's Kart:
Win the All Cup Tour in mirror mode.

Waluigi's Kart:
Win the Flower Cup in the 100cc class.

Staff ghost racers
Beat these record times to unlock a staff ghost racer for each track.
Baby Park: 1:14.000
Bowser's Castle: 2:47.000
Daisy Cruiser: 1:55.000
Dino Dino Jungle: 2:03.000
DK Mountain: 2:15.000
Dry Dry Desert: 1:53.000
Luigi Circuit: 1:29.000
Mario Circuit: 1:44.000
Mushroom Bridge: 1:34.000
Mushroom City: 1:53.000
Peach Beach: 1:15.000
Rainbow Road: 3:19.000
Sherbet Land: 1:28.000
Waluigi Stadium: 2:02.000
Wario Colloseum: 2:24.000
Yoshi's Circuit: 2:02.000

Ride as mr. game and watch
First, press abrlza very fast. After play as every character and play as every partner, then type zzzaaabzlra very fast, then you will race mr. game and watch. After when you beat him, he will be yours to play as and he will be very very fast.
submitted by: Wierdo

Mushroom city boosts
Mushroom-looking vehicles cluttering the road on the Mushroom City course, unlike other vehicles on the track, will not send your racer into a spin if bumped into. Instead, bump into one of the mushroom vehicles and they'll drop a mushroom item that you can use for a turbo boost.

Boost After Revival
At times you may be replanted on the track by a floating ally, usually after you've fallen off of the track. To get a free boost as he drops you, hit the accelerator just before you touch the ground. The timing is tricky, but it's worth the effort.

New Title Screen
Once you have recieved the gold trophy on Mushroom, Flower, Star, Special Cups, and The All Cup Tour on 50CC, 100CC, 150CC, and Mirror mode, like in Mario Kart 64 you will be rewarded with a new title screen featuring all of the racers.

Unlock End Credits
You must complete three things on one Grand Pirx race. Three options follow. Pick one of each, and when the cup is over, you'll view the credits.

- Cup: Special Cup or All-Cup Tour
- first or second place
- 100CC or 150CC

Lightning Safe
If a lightning bolt is used right when you get hit by a shell, banana, etc.-you won’t get hurt. Same if you fall off the course.

Alternate Routes
These alternate routes, while not always faster than the normal route, may often give you more items than you'd normally get!

Luigi Circuit: After you go off the first speed boost jump after the starting gate, if you hang a right there is a little path behind the chain chomp post. Before the second U-turn, there is another alternate route behind some pipes. I found it's not much use. (These for Luigi Circuit only work in 100cc, 150cc.)

Peach Beach: Before the first item row, there is a left turn that leads you into a pipe that shoots you out into a double item. Unfortunately, it does not help you any. Before the finish line, instead of going straight, turn left and go around the fountain. There are 2 double items, but it's longer to go that way.

Mushroom Bridge: Right after the starting line there is a ramp to the sharp right. Take it, go through a pipe, and you are shot out to receive a double item. This one is also longer than just going on the track. Also, after the first tunnel, there is a road to the left. Take it to avoid all the cars on this stretch of road and get an item.

Mario Circuit: In Mirror mode, use a mushroom to go behind the chain chomp through the grass. If you can do it right, it removes a few secs from your time. I found it best to use a light kart.

Bowser’s Castle: In the big room where there is a bowser shooting fire balls instead of going around the U turn like part go straight forward in to a gap on the side of the track. Make sure you don’t just drive into it you have to power slide to the right otherwise you will fall right off the other side!

Starting Line Boost
When you fall off the track, when the little cloud man bring you back to the track, if you press the gas button right when the wheels touch the ground, you'll also get a little boost. Courtesy of fUble_baSs.

You get a boost at the start if you press A right after the lights turn green. You can also get a much larger boost though in co-op when both players press A at the same time. Courtesy of Duncan.

To receive a boost at the beginning of a race, hit A at the same time the announcer says go. If timed correctly, you will jump to the head of the pack.