View Ending and Credits
At the title screen, hold A. Hold B for a brief moment twice, then release A and hold B. Now hold A for brief moments twice, then release B, then press Start.
View Secret Credits
At the credits, hold A. Hold B for a brief moment twice, then release A and hold B. Now hold A for brief moments twice, then release B, then press Start. This will show you some additional developer names in Chinese at the end. (This will happen automatically if you happen to use the cheat described previously to view the ending.)