Hints:
Master Cheat: At the character selection screen hold these buttons together on controllers #1 and # 4: L + R + Left Analog-stick + Right Analog-stick + X + Y 
Crazy X Secrets: After completing a level of Crazy X, you will receive the prize shown: 

Level 1: Unlocks course maps for West Coast, Glitter Oasis, and Small Apple 
Level 2: Unlocks the bike, stroller, and carriage to use as vehicles 
Level 3: Unlocks ''Another Day'' mode 
Level S-S: Unlocks all 12 drivers for each course 

Expert Mode: At the character select screen hold White and Black and press A to select a character. 

No Arrows: At the character select screen hold White and press A to select a character. 

No Destination Mark: At the character select screen hold Black and press A to select a character.