C-ya, C-Serpent:

When you're facing off against the first boss, the C-Serpent, let it hit you with a fireball, and while you're still in your moment of invincibility, quickly jump on its head, go up, and you win the battle. It's as simple as that. NOTE: Will not work on the C-Serpent in Zoda's Revenge: StarTropics 2.

 

Get Max Life:

The big heart located before the Big Rock tunnel will reappear everytime you have to continue so if you keep dieing and continuing you can keep getting one more heart until you have max health. You can also continue getting the heart after you have max health if you die in the tunnel. Kudos to my girlfriend Anita for figuring this one out!

 

Password:

When you get to the end of Level 4 where the robot asks for a password, put in 747.