Hole-in-One Contest:
At the Title Screen, hold Z and press Start. Then select "Special Contests".

Super Topspin, Super Backspin:
When you are about to hit the ball use manual, then when it comes back instead of hitting ''AA'' for Topspin hit ''AB'' for Super Topspin, and instead of hitting ''BB'' for Backspin hit ''BA'' and you will get Super Backspin.

Get Better Versions of All Characters:
Beat each player in a Vs. character match when an envelope appears next to their character select symbol on the Vs. screen.

Extra Tournaments:
At the Title screen, press Start + Z to open up 'Special Contests' at the main menu. You'll find a Hole in One Contest as well as a code screen for special password tournaments.

Thanks to Revolution readers Harvey Wallbanger, MIkemac2417, the shiny1, JLuther, Timmy, Steven, jeff gordons dude, laotzo, keepa, and Joejoe645!