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.