Pokemon Statium Codes
Battle Mewtwo-
To unlock a hidden 6-on-1 battle with Mewtwo, beat the Gym Leader Castle and get trophies in all 10 tournaments in the Stadium Mode. The map screen will now turn to a night scene and a bonus tournament will open up in which you battle against the psychic super-Pokemon, Mewtwo (#150). Once you beat Mewtwo, you unlock a new game mode.
Bonus Stickers-
Once you have beaten both the R-1 mode (including Mewtwo) and the R-2 Mode (including Mewtwo), you are given a set of bonus stickers that you can access in the Gallery Mode. When you're on the Gallery main screen, press and hold L and R and move the Cursor to Print. If you keep the buttons pressed, the Print option will now change to Bonus. You will now have access to a set of 16 bonus "wallpaper" stickers from all the different modes that you can print out at "Snap" Stations
GB Speed Upgrades-
There are two secret speed upgrades to the GB Tower Game Boy emulator that let you play Pokemon Red, Blue and Yellow at much higher speeds:
Doduo Mode: Beat the Poké Cup. Once you have won all the Poké Cup tournaments, the GB Tower changes into Doduo GB Tower and a Doduo sticker appears on the Game Boy. The Doduo upgrade doubles the speed of the game play when playing the Game Boy game on your N64.
Dodrio Mode: Play the Game Boy games at hyper speed with this alternate speed settings. To get it, you need to beat the Prime Cup (after you have already beaten the Poké Cup).
Get Amnesia Psyduck-
Well, it's hidden deep in Pokemon Stadium. Unlocking it will take a while, but it's definitely worth it. You have to register ALL 151 Pokemon in the Hall of Fame. Whenever you beat a tournament (or Gym Leader Castle), your six Pokemon are entered into the Hall of Fame. It doesn't matter whether you use rental Pokemon or your own, but you can't have any gaps. Once you've filled it all up, you are awarded a free Psyduck bonus Pokemon that knows the Amnesia technique.
Get Surfing Pikachu-
Yes, it's true: Surfing Pikachu is hidden in Pokémon Stadium. To teach your Pikachu Surf (a technique it can normally not learn), you need to first unlock the R-2 (Round 2) mode. Then do the following:
Enter the R-2 Prime Cup's Master Ball division (you have to beat the first three divisions first).
Assemble a team that contains a Pikachu that does not yet know Surf. You HAVE to use a Pikachu from your Game Boy game. You cannot unlock Surfing Pikachu using a Rental Pokémon.
Do not register your team! Pick it directly from your Game Boy cartridge.
You now have to beat the Prime Cup's Master Ball division using a three-Pokémon team that always contains Pikachu. Pikachu has to be in every one of the eight battles.
You are not allowed to use any continues. If you do, you won't get Surfing Pikachu.
Once you have fulfilled all the above conditions and beaten the cup, you are shown an award screen with Pikachu standing on a surfboard. From here on, Pikachu can use the Surf technique both in battle and during gameplay (Game Boy versions only). If you've got Pokémon Yellow, you can now also access the hidden Surfing Pikachu mini-game. Simply go to the small hut on the northern beach of Route 19.
Kids Club: Hyper CPU Difficulty-
To unlock this hidden difficulty setting, select a single-player game against three CPU-controlled opponents. You need to win the "Who's the Best?" challenge five times in a row on HARD difficulty. This will open up the new Hyper difficulty setting for the CPU players.
New Title Screen-
Beat both the Gym Leader Castle and Stadium modes to change the title screen (in addition to the map mode). The new title shows depict Pikachu, Blastoise, Charizard, Venusaur and Mewtwo.
Open Up R-2 Mode-
To get the secret R-2 Mode (as well as a brand-new title screen) defeat Mewtwo after you have beaten the Stadium Mode and Gym Leader Castle Mode. You will now see the final credits sequence, which will unlock the harder R-2 Mode and all new battles. You can toggle between R-2 and Regular Mode at the start-up screen by pressing C-Right.
Rent Mew-
Many of you have asked how you can get all 151 trophies in the Hall of Fame if you don't own the elusive bonus Pokemon Mew. No problem: Once you open up R-2 Mode, you can rent and use Mew in the Prime Cup (sorry -- you still can't get Mew in Gym Leader Castle and Free Battle).
Talking Pikachu-
For a talking Pikachu, you need to upload one from Pokemon Yellow, Rental, Red, and Blue versions will just be silent.
Pokemon Statium Codes 
