Farfetch’d is...well, farfetched. Farfetch’d doesn’t evolve, or have any evolved forms, and it’s a Normal/ Flying type Pokémon.
In Red and Blue Versions, you can get a Farfetch’d by trading a Spearow to a girl in Vermillion City. The house she lives in is the one right below the Pokémon Center, and a little to the right. The Farfetch’d you get will be whatever level the Spearow you traded was, and will be named “DUX”.
In Yellow Version, you can catch Farfetch’d on Routes 12 and 13, as well as trade them from Red, Blue, another Yellow, Gold, Silver, or Crystal. When you trade a Farfetch’d from Red, Blue, or Yellow to Gold, Silver, or Crystal, it will be holding a Bitter Berry, which heals Confusion in the second generation games.
Hope you enjoy the farfetched Farfetch’d!