Random Level
Enter: Z+A at the Level Select screen.
(Thanks to Gellink)

Random Robot
Enter: Z+A at the Robot Selection screen.
(Thanks to Gellink)

3 New Cars
On the car selection screen, hold the Top, Bottom, and Left C buttons. While you’re holding these buttons, scroll through the 4 cars. Three of them will be replaced with a school bus, an ATV and a police car.
(Thanks to Yillun)

Flashing Lights
Complete a course with a top 10 time on it. When your intials are entered, press Down until you see the conveyor, then press Left. Hold Left until you see a head go by saying, ”I love this job.” Select the Police Car or the School Bus and press BRAKE, BRAKE, GAS while in the race to activate the flashing lights on it.
(Thanks to Yillun)

Secret Stages
At the Choose Race screen, hold the following for hidden courses:
Golden Gate Park - L Button + Left C + Down C.
Indiana - L Button + Up C + Right C.
San Francisco - L Button + Right C + Down C.
(Thanks to Yillun)

Big Head Crash
Pause the game, hold the block/dodge button and press: Punch-Punch-Kick-Jump.
(Thanks to Shirack)

Goar Skin
Jack 30 Goars.
(Thanks to Shirack)

Koo-Ala Skin
Defeat 150 Koo-Alas.
(Thanks to Shirack)

Ratnician Skin
Defeat 200 Ratnicians.
(Thanks to Shirack)

Rhinoroller Skin
Jack 30 Rhinrollers.
(Thanks to Shirack)

Shadow Crash
Pause the game, hold the block/dodge button and press: Kick-Punch-Kick-Jump.
(Thanks to Shirack)

Snipe Skin
Jack 50 Snipes.
(Thanks to Shirack)

Spike Skin
Jack 50 Spikes.
(Thanks to Shirack)

Skip Level
Press: Right, I, Left, II, Up, Select, Down, Select at the Title screen.
In the game, hold Up + Right, and press I + II + Select.
(Thanks to RogerTHAT)

Sound Test
Press: Left, Right, I, II, Down, Select, Up, Select at the Title screen.
(Thanks to RogerTHAT)

Begin in Level 6 with the Red Crystal
Enter: OZKQ EXY1 WH4S REQA
(Thanks to Accerat)

Ending #1
Enter: RIG7 NVFX E45V 07BT
(Thanks to Accerat)

Ending #2
Enter: OYZY UQAU R12S SMIA
(Thanks to Accerat)

Ending #3
Enter: C1DF O26D L1KN SWJK
(Thanks to Accerat)

Fight Dracula
Enter: 7MEF 0VFT 151Z Y2Z5
(Thanks to Accerat)

Get All Items
Enter: PSPR VRBV U2DT RFIZ
(Thanks to Accerat)

Get Dracula’s Rib, Chain Whip and Blue Crystal
Enter: OFIT M5QX 1P5S QBQA
(Thanks to Accerat)

Get Dracula’s Rib, Chain Whip, Blue Crystal and Dracula’s Heart
Enter: SZMH QXE1 5PXW UESE
(Thanks to Accerat)

Get Dracula’s Rib, Chain Whip, Blue Crystal, Dracula’s Heart, Dracula’s Nail, Flame Whip and Red Crystal
Enter: TIRH DYDZ 405V 81B1
(Thanks to Accerat)

Get Full Experience and All Items
Enter: DINT XXDY 445X V3ZX
(Thanks to Accerat)

Get Thorn Whip and Holy Water
Enter: OFIC M5YX XD4C Q3AA
(Thanks to Accerat)

Super Alley Ball
Trade up to the jumbo prize in Alley Ball or Test Your Strength.
(Thanks to Kinger)

Super Balloon Darts
Trade up to the jumbo prize in Balloon Darts or Bowler Coaster.
(Thanks to Kinger)

Super Circle Drop
Trade up to the jumbo prize in Nerves-o-Steel or Lucky Cups.
(Thanks to Kinger)

Super Day at the Races
Trade up to the jumbo prize in Day at the Races or Dunk Tank.
(Thanks to Kinger)

Super Hole in One
Trade up to the jumbo prize in Clown Splash or Hole in One.
(Thanks to Kinger)

Super Hoops
Trade up to the jumbo prize in Hoops or Collection Plate.
(Thanks to Kinger)

Super Old West Shootout
Trade up to the jumbo prize in Shoot for the Stars or Buckets of Fun.
(Thanks to Kinger)

Super Pigskin Pass
Trade up to the jumbo prize in Shooting Gallery or Pigskin Pass.
(Thanks to Kinger)

Super Ring Toss
Trade up to the jumbo prize in Ring Toss or Ka-Pow.
(Thanks to Kinger)

Super Spilled Milk
Trade up to the jumbo prize in Spilled Milk or Frog Leap.
(Thanks to Kinger)

Black Ninja Suit
Take a picture of all the students of Bullworth.
(Thanks to SmashPirate)

BMX Helmet
Complete all bike races.
(Thanks to SmashPirate)

Crash Helmet
Win the first set of Go-Kart races.
(Thanks to SmashPirate)

Double Carnival Tickets
Collect all G & G cards.
(Thanks to SmashPirate)

Fireman’s Hat
Pull the fire alarm 15 times.
(Thanks to SmashPirate)

Mo-Ped
Buy from carnival for 75 tickets.
(Thanks to SmashPirate)

Pirate Hat
Beat up the pirate on the island near the pirate ship.
(Thanks to SmashPirate)

Pumpkin Head
Smash all pumpkins either on Halloween or in basement.
(Thanks to SmashPirate)

Robber Mask
Break into 15 lockers without getting caught.
(Thanks to SmashPirate)

Rubber Band Ball
Collect all rubber bands.
(Thanks to SmashPirate)

Spandex Bike Shorts
Bike 100km.
(Thanks to SmashPirate)

Blox Time
Enable Slow-mo in Single Player Mode.
(Thanks to Lemmy)

Flower Power
Converts explosion effects to flower explosions.
(Thanks to Lemmy)

Maestro
Converts base blocks to jingle blocks.
(Thanks to Lemmy)

My Team
Convert all Cheerleaders to Profile Character.
(Thanks to Lemmy)

Tool Pool
Unlock all toys in Create Mode.
(Thanks to Lemmy)

Black & White
Complete Campaign 2 in Arcade Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Choose Ship
Complete Campaign 4 in Arcade Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Extra Bullet Sounds
Complete Campaign 5 in Arcade Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Extra Hit Sounds
Complete Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Extra Skin Settings
Complete Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Flip
Complete Campaign 2 in Arcade Mode on Ace difficulty.
(Thanks to NoInt3r3st)

Gunroar
Complete Campaign 4 in Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Hyper Speed
Complete Campaign 1 in Arcade Mode on Ace difficulty.
(Thanks to NoInt3r3st)

Ninety Nine
Complete Campaign 2 in Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Torus Trooper
Complete Campaign 3 in Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

TUMIKI Folder
Complete Campaign 5 in Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Turtle Speed
Complete Campaign 1 in Campaign Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Unlock Original TUMIKI Fighters
Beat all five campaigns on any difficulty.
(Thanks to NoInt3r3st)

Virtual
Complete Campaign 3 in Arcade Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Wireframe
Complete Campaign 1 in Arcade Mode on Pilot difficulty.
(Thanks to NoInt3r3st)

Fight Bosses
After the last hit (a punch) in Wang, immediately hold 1 and 2 buttons together and press Up and Down alternately until the final screen disappears. Doing this correctly means you play against the 6 bosses again.
(Thanks to Amardo)

Infinite Lives
Push Button 1 at the Title screen. Hold the Reset button at the black screen (after the red screen) until Riki appears on the screen. Release Reset and when the game starts, you should have infinite lives.
(Thanks to Amardo)