Harder Computer Opponents:
Enter the Vs. Mode and set the Mode to COM. Hold [L]+[R]+X and then press START to begin the game (and hear "Yoshi" to confirm the code). Once you begin playing, your opponents will change color and become much more difficult to beat.
Bonus Game:
On the Title Screen, select ACTION MODE and press START. Set the Round to 10, the speed to HI, and the Music Type to OFF. Press CNTRL II: [L]+[R]+SELECT+START simultaneously. You will hear "Yoshi", and will now be able to set the Round for the game's later stages.
Passwords: Use the controller to choose a starting round beyond 10 to enter a password...
5G9SVLM 5-5 96?VY5| 7-5 7X5BV52 9-5
TWPSV0V 6-5 F_96VL2 8-5 J4JDVY2 10-5