Hints:

Pokemon colors:
Naming any pokemon "PIXEL" will change its color.
Ninetales: PIXEL/NINELAR: darker red tails. NINE-TALES: yellow tails
Rhyhorn: PIXEL: blue mouth
Rhydon: DEATSENTEN: purple. PIXEL: ?
Bulbasaur: BULANCE: yellow, green and blue. PIXEL: ?
Articuno: SNOWY: darker blue. PIXEL: ?
Pikachu: YELLOW RAT: orange PIXEL: ? 

Alternate Pokemon Colors:
     Did  you  ever  notice  how  some  of  the Pokemon that appear in
Pok©mon  Stadium  have  different  colors?  The  secret  to  the color
variations  lie  in  the  names  you give your Pok©mon as well as your
trainer  ID  number  (assiged  to  you in Pokemon Blue, Red or Yellow,
whenever  you  start  a  new game). While there are a few secret names
that  change  only  certain  Pokemon's  colors, there are a few naming
tricks that result in different color variations. For example:

Use only lower caps (ie: poliwhirl)
Reverse the syllables (ie: DRILLBEE)
Abridge the names (ie: Pika) 

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.

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.

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 Pok© Cup. Once you have won all the Pok© 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 Pok© Cup). You can switch between
the  different  GB  Tower speed settings during gameplay by pressing C
Right.

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.

Get Amnesia Psyduck:
     Have  you  ever  wondered  how  you  can  get the elusive Amnesia
technique?  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 Pok©mon 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
Pok©mon.  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-Pok©mon  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
Pok©mon  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.

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.

Win Bonus Pok©mon:
     Each  time  you  beat  the Gym Leader Castle (including the Final
Four  and your Rival), you will receive one of eight semi-rare to rare
Pokemon.  These  Pokemon  are  awarded  at random, so it's likely that
you'll  need  to beat the Gym Leader Castle again and again to get the
ones  you  want.  Note  that once you have beaten the Castle, you only
need  to defeat the Final Four and your Rival again if you want to win
more Pokemon.

Here are the Pokemon you can win:
#001 Bulbasaur
#004 Charmander
#007 Squirtle
#106 Hitmonlee
#107 Hitmonchan
#133 Eevee
#138 Omanyte
#140 Kabuto 

More Damage:
     When  executing  a  fighting move, hold A when the description of
the move is displayed.

All Pokemon:
     If  you  win  the tournament on hard, you can get all the pokemon
(including all pokegods).

Pok©mon Stadium Cup requirements:
Pika Cup:
Pok©mon can only be between level 15-20. 

Petit Cup:
     Level ranges between 25-30. There is a height requirement though.
Height 6'8" limit and weight 44 pounds.

Pok© Cup:
     Only  can  use  3 Pok©mon, levels 50-55. The sum of the Pok©mon's
levels cannot exceed 155.

Prime Cup:
     Everything  is  legal. You can have any level, height, weight, or
number of Pok©mon. However, your opponents' levels are always 100.

Faster Game Speed:
     Beat  the game on prime cup (master ball) and go to gb (game boy)
tower  and press C-Right or C-Left and a sticker will be there amd the
game will go faster.

Get Togepi:
     Get  a Bulbasuar, and fight and win against Venusaur, Mewtwo, and
Blastoise.  After  you have beaten them, go to Pokemon Lab and use the
new  item  called  Toge-Stone.  Use  it on Bulbasuar and you will have
Togepi.

ChronoMew:
     (Note:   you  have  to  catch  Bulbasaur,  Charmander,  Squirtle,
Pikachu,  Omastar  and  Ninetales!)  To get ChronoMew you have to pick
Bulbasaur,  Charmander,  Squirtle, Pikachu, Omastar and Ninetales then
at the battle screen press A, B, B, A, C-Left, C-Right then START. You
should  hear  a  mew's  cry  then gets lower then growls. It'll pause,
press  start  to  battle  with  your new ChronoMew. (WARNING!!! If you
press  any diffrent button to start the battle all data will be erased
that is all.) Get Snubbles:
     Go  to  the  main screen and type in A, B, Z, Z, R, L, L, C-Left.
You will here a noise that represents that is worked.

Mew:
     Mew  will  become playable, as a "Rental" Pok©mon, in the Round 2
version  of  the  game.  He  can  only  be  played  in  the  Prime Cup
tournament, Gym Leader's Castle, Free Battle, and Mewtwo Battle modes.

Kids Club Hyper mode:
     In   one   player  mode  with  three  CPU  controlled  opponents,
successfully  complete "Who's the best?" five consecutive times on the
hard  difficulty setting within one match. Hyper will be unlocked as a
new difficulty setting for CPU controlled players.

Avoid recoil damage:
     If  you  use  an  attack  that  you  know  will kill the opposing
Pok©mon, but will hit you with the recoil, make sure that your Pok©mon
has  at  least  20 HP left. Use the attack and you will not suffer the
recoil damage.

Trade with out a second transfer pak:
     Put a box on the game, then put the Pokemon from a different game
or  the  same one in the box. Then, go back to the lab and put the box
back  on the game that you are trading to, go to the box, and withdraw
the  Pokemon  when  you  want  or  need it. Note: This also works with
items.

Missingno warning:
     Do  not transfer Missingno to Pokemon Stadium. It will glitch the
game and make it unplayable.

More damage (Japanese ver.):
     Note:  This is for the first Pokemon Stadium game from Japan, not
to be confused with the North American Pokemon Stadium.

     Execute  a fighting move, then hold A when the description of the
move is displayed.

Get Pok©mon presents faster:
     Successfully  complete  the Gym Leader Castle. Then when you want
to  complete it again, go to the Gym Leader Castle, go directly to the
Elite 4, and defeat your rival.

Bonus stickers:
     Successfully complete R-1 mode, defeat Mewtwo, complete R-2 mode,
and defeat Mewtwo again. Enter the gallery screen, then hold L + R and
highlight  the  "Print" option. Keep holding the buttons until "Print"
changes to "Bonus" to access sixteen more stickers.

Start with all three beginning Pok©mon:
     When you start a new game, you can start with all three beginning
Pok©mon  by  starting  over  and  choosing one of them in the Game Boy
Pok©mon  game. Then, capture a Pidgey or Rattata. Save it to the boxes
on  Pok©mon  Stadium.  Repeat the steps with a different Pok©mon until
you  get  all  three. You can also save and keep Pok©mon from your old
game that you still want before starting over.

Talking Pikachu:
     For  a  talking  Pikachu,  you  need  to  upload one from Pokemon
Yellow. Rental, Red, and Blue versions will just be silent.

Rainbow Blastoise :
     If  you have a "BLASTOISE" then must you call him "COLORMAN" then
have you a rainbow "BLASTOISE"

Hint:
     When a Pokemon flys or digs underground use a swift attack. NOTE:
This attack never misses when the emeny digs or flys.