First Appearance: Pokémon Red/Blue
Patience is a virtue. Those that sat on Magikarp for 20 levels know that for sure. Having to switch Magikarp out for a stronger pokemon to win battles was a long, grueling process, but Gyrados made it totally worth it.
When you threw Gyrados out in a battle, you had to check your friend to see if he would lose his poker face. Of course it never failed.