Sound test - At the title screen, press Left + A + C-Left + C-Right + Start. 

Bonus ending - Get an "A" on every level and collect the fifty-two gold gems. Then during the ending sequence, hit the target on Teren that appears for a slightly different version. 

Bonus levels - Collect all fifty-two gold gems and view the entire ending sequence. Press R after the last screen with the stages appears to access twelve bonus levels. 

Skip introduction sequences - Press Z. 

Faster speed - Repeatedly tap Right during any of the running sequences to move faster and win the race. 

Hints: 

Creating a clanbomb - Place four Bombs into a clanpot and shake it to create a Clanbomb. 
Creating a ninja start - Place two Flowers into a clanpot and shake it to create a Ninja Star. 
Creating a Boomerang - Place three Ninja Stars into a clanpot and shake it to create a Boomerang. 
Creating a Green Gem - Place six Blue Gems into a clanpot and shake it to create a Green Gem. 
Creating a Gold Gem - Place two Green Gems into a clanpot and shake it to create a Gold Gem. 
Getting Red Gems - Shack the first Clancer in level 3-8 to get thirty gems. Exit the level and start it again for another thirty gems. 
Getting Mole's Gold Gem - Throw the mole into the air, then hit his stomach to get his gold gem. 
Quicker Lunar level - Shake the missiles on the Lunar level to make them bigger. It will take less time to complete the stage if this is done. 
Defeating Tarus - When you pick up the robot's foot, shake him to the ground. Then shake him up and quickly shake down.

Game Shark Codes:

Infinite Health 810ED0E0 03E8 
Infinite Red Gems 81175B66 270F 
Press GS Button For First 16 Gold Gems 8916F546 FFFF 
Press GS Button For Second 16 Gold Gems 8916F544 FFFF 
Press GS Button For Third 16 Gold Gems 8916F542 FFFF 
Press GS Button For World Modifier 88175B85 00?? 
Press GS Button For Level Modifier 88175B87 00?? 
Press C-Right For Quick Speed Right D0183A35 0001   810ED0DC 0008 
Press C-Left For Quick Speed Left D0183A35 0002   810ED0DC FFF7 
Press C-Up For Quick Speed Up D0183A35 0008   810ED0F0 0006 
Press C-Right For Quicker Speed Right [Note] D0183A35 0001   810ED0DC 0010 
Press C-Left For Quicker Speed Left [Note] D0183A35 0002   810ED0DC FFEF 

Quantity Digits to Accompany World Modifier Code 
02 - World 1-X
0C - World 2-X
18 - World 3-X
25 - World 4-X
31 - World 5-X 

Quantity Digits to Accompany Level Modifier Code 
00 - Level 1
01 - Level 2
02 - Level 3
03 - Level 4
04 - Level 5
05 - Level 6
06 - Level 7
07 - Level 8
08 - Level 9
09 - Level 10
0A - Level 11
0B - Level 12 

Note: You can also go through most walls with this code.