Alakazam, the original badass Psychic Pokémon. You caught the elusive Abra, and while it required some babying, it was a monster once evolved. Then, you could trade it with a trusted friend, and it began kicking ass seven ways to Sunday, nuking its way through the game. While Alakazam might not have the most diverse level-up moveset out there (Recover and Disable stand out), it has everything it requires between Psychic and Recover.
That sweet IQ and awesome mustache doesn't hurt either. Alakazam is a 'mon that flings its opponents across the room, then convinces them to fling themselves back again, and then makes them apologize for making noise while doing so. It's the sort of Pokémon that does whatever it damn pleases.