Pokemon Stadium: Codes
Win the Rival Cup to receive a Farfetch'd that knows Baton Pass.
Gligar with Earthquake
Win the Rival Cup in Round 2 to receive a Gligar that knows Earthquake.
Differnent Title Screen
Win all the Stadium Cups in Round 1 to change the title screen. Win all the Stadium Cups in Round 2 to change it again.
Doduo and Dodrio modes (RBY)
If you beat the Stadium or Gym Leader Castle for the first time, you'll upgrade the GB Tower to the Doduo GB Tower which can only be used for Red, Blue, and Yellow. Now beat the other mode that you didn't beat the first time and you'll unlock the Dodrio GB Tower mode which lets you play your RBY game 3 times as fast.
Doduo and Dodrio modes (GS)
To unlock the Doduo GB Tower for Gold or Silver you must beat the Stadium or Gym Leader Castle in Round 2. To unlock the Dodrio GB Tower, beat the other one in Round 2.
Rival Cup / Round 2
Win all the Stadium Cups and defeat all the Gym Leader Castle trainers to unlock the Rival Cup. Defeat your Rival to open up Round 2.
Celebi Rental
Unlock Round 2 to access Celebi as a rental Pokémon in the Prime Cup competition.
Super Hard Mini-Game Difficulty
Defeat the CPU in a seven-coin mini-game under the hard difficulty setting.
Personalized Mini-Games
Have a Pokémon game in the transfer pack when you play the mini-games. The game will search for Pokémon that you own for use in the mini-games.