CHEATS:
Enter these at the code-selection screen, then press 
Start to get past the bosses/jump levels
 
What it is - What it does
7543-2857-8141-2141 - Blast Hornet
8573-2257-6241-1141 - Toxic Seahorse
2563-4265-6357-5127 - Tunnel Rhino
2373-4267-4357-7727 - Volt Catfish
4478-4863-4627-7358 - Crush Crawfish
6414-4155-6872-3356 - Ninth Chip
5718-1263-2627-7458 - Dr. Doppler's Lab
 
These cheats give special powers:
6414-4155-6872-3356 - Have everything except the super adaptions
1454-3535-6162-7162 - Zero's beam sabre + everything from the above code
 

Super Passwords  
The following passwords give you all items , and 3 of 4 enhancement chips, 
without any bosses beaten. The enhancement chips given are listed below the 
password. 

8 1 2 7 
4 5 3 5 
6 3 1 6 
5 3 1 1 

Super Armor, Dual Air Dash and Hyper Crash 

8 1 2 7 
4 5 6 5 
6 3 1 6 
5 3 1 6 

Super Armor, Dual Air Dash and Energy Recharge 

8 1 2 7 
4 5 6 5 
6 3 1 6 
5 3 5 1 

Super Armor, Hyper Crash and Energy Recharge 

8 1 2 7 
4 3 6 5 
6 3 1 6 
5 3 1 1 

Dual Air Dash, Hyper Crash and Energy Recharge