Pokémon X and Y Walkthrough, Pokémon Move Sets: Farfetch'd
(Please note that the recommendations below are largely made for in-game play. A Farfetch'd in a competitive environment - why are you using Farfetch'd in a competition, by the way? - will likely make use of different moves to accommodate for smarter, more adaptive opponents. If you have an alternative moveset, list it in the comments.)
Oh, Farfetch'd. One of the oldest of pokémon, Farfetch'd is also one of the least-loved by its parent company. It has received almost no revamps over the years, and the few advantages it has been granted have never lifted Farfetch'd out of the lowest tiers of fully-evolved pokémon. It's a groovy little bird, though, and out of sheer love (as well as my girlfriends insistence) I will help you craft a serviceable Farfetch'd. It won't win any tournaments, but it may prove more helpful than you'd think.
Type: Normal / Flying
Farfetch'd does not evolve into or from any other pokémon. C'mon, Gamefreak, get on that already. This poor little guy needs him an evolution.
Bug, Grass. Immune to Ghost and Ground.
Electric, Ice, Rock.
Poor Farfetch'd. This flying-type has gotten the shaft since the first generation, despite being a fan favourite for a looooong time, and the sixth generation hasn't been any kinder to him as far as stats are concerned. Farfetch'd is below average in every stat, failing to raise any of its base stats even into the 70s. Attack is its standout stat, which is good since it's the one you'll rely on the most for an effective Farfetch'd, but it's still substandard for an attacking pokémon. Everything else is barely serviceable.
Keen Eye: Nothing can reduce this pokemon's accuracy. Additionally, moves used to increase the enemy pokemon's evasiveness will mean nothing to this pokémon. Keen Eye is by far the standout ability for Farfetch'd, and if nothing else can turn it intoa determined little sniper when you're facing pokémon that love to use Double Team.
Inner Focus: This pokémon is never subject to flinch. An okay ability on other pokémon, but seldom the top choice. It's largely worthless on Farfetch'd, which will... uh... generally die when it's hit. Who cares about flinching?
Defiant: If the pokémon is hit by a move or ability that lowers one of its stats, it will receive a substantial boost to its Attack. Very handy if you're sending your Farfetch'd up against something with, say, Intimidate, though this is generally an incidental ability that you can't count on. Might as well get it if you can, though. Defiant is a hidden ability.
Let's be honest, Farfetch'd just isn't a good pokémon. Nevertheless, there are a few ways to make it into a non-competitive rumbler. Probably your best bet is to focus on Farfetch'd's best move, Brave Bird, which gives Farfetch'd STAB damage. Swords Dance increases its already potent damage, Agility helps Farfetch'd go first, and Attract / Swagger confuses your opponent into potentially not attacking. If you think your Farfetch'd is durable enough to survive an attack, you can use another attacking move instead; I like U-Turn, personally, as it will sweep Farfetch'd out of danger's path to fight another day.
The other move pool consists of moves that take advantage of Farfetch'd's high critical rate with its Stick. Set it up with Slash, Night Slash and Air Slash to cover the high-critical bases, then toss in Swords Dance to up its Attack. You may also want toss in U-Turn as a way of surprising opponents with an abrupt departure. Poison Jab is a possibility in this moveset, and can turn Farfetch'd into a fairy-type killer... albeit a rather mediocre one.
EV / Super Training
Farfetch'd is all about two stats: Attack and Speed. Boost these at the expense of all others and your Farfetch'd will rack up at least the occasional kill. Allocating EVs to other stats is a waste of time, as they'll never get high enough to make a difference to your Farfetch'd. It's also very important to choose a Nature compatible with one of these stats while not detrimental to the other, in which case I'd recommend either Adamant or Jolly. Both sacrifice on Special Attack, which is seldom of much use to Farfetch'd.
Catching a Farfetch'd
There are two ways to catch a Farfetch'd in Pokémon X and Y. The first is to proceed to Route 22's early sections and wander around in the grass for a while. You will, eventually, run afoul (pun!) of a Farfetch'd. The alternative is to trade a Bunnelby to a man in Santalune City for a Farfetch'd. Bunnelby are quite numerous, so this should be an easy trade to make.
Regardless of your method of acquisition, I suggest hunting down wild Farfetch'd simply for getting a Stick. A Farfetch'd can work without a Stick, but the boost to its critical attacks is crucial to doing a lot of damage. Without criticals this little bird won't succeed at much of anything.