Did you ever notice how some of the Pokémon that appear in Pokémon 
Stadium have different colors? The secret to the color variations 
lie in the names you give your Pokémon 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)