You really ought to look into farfetch’d, Falkner. Those are good, reliable pokémon.
Edit: I have just been informed by my editor that this response may be considered “rude.”
It’s difficult to say what, objectively, makes a pokémon so great, anonymous. In my personal opinion, I find its protective flocking habits to be fascinating: that’s unusual for a final-stage bird pokémon. Most others prefer living on their own or controlling vast amounts of territory that their pre-evolutions just happen to live on. Swellow, on the other hand, live in true communities, and it’s quite inspiring to see the lengths they would go to in order to protect their flocks.
Of course, that’s just my opinion, and other people are certainly welcome to disagree or to find something else even more fascinating about swellow.
The Pokédex According to Bill 