Pokémon X and Y Walkthrough, Pokémon Move Sets: Durant
(Please note that the recommendations below are largely made for in-game play. A Durant in a competitive environment will likely make use of different moves to accommodate for smarter, more adaptive opponents. If you've got a different moveset on your Durant, by all means, share it with us in the comments.)
For quite a while, Scizor monopolized on the bug- and steel- market. Then, one day, along came an ant to bust up its party. Though arguably not as cool or as strong as Scizor, Durant is quite a potent pokémon in its own right - and with some work, you can transform this little insect into a fiend of a sweeper.
Type: Bug / Steel
Durant does not evolve to or from any other pokémon.
Bug, Dragon, Fairy, Grass, Ice, Normal, Psychic, Steel. Immune to Poison.
Durant is a study in contrasts. Its HP, Special Attack and Special Defense are all fairly abysmal. By contrast, its Attack, Defense, and Speed are all through the roof. In other words, Durant can be highly effective in some situations - and a complete pushover in others. Fortunately, Durant's stats are weighted in such a way that it will usually have the advantage, so long as it's properly trained.
Swarm: Bug-type attacks will increase by half if the pokémon only has one-third or less of its HP remaining. On a beefier pokémon, this would be useful; on Durant, which is very much an all-or-nothing brute with low HP, it's not so great. Pass.
Hustle: Durant's Attack stat is boosted by half. As a tradeoff, its overall accuracy with physical moves is lowered by one-fifth. Despite the drop in accuracy, Hustle is a horrifyingly-powerful move which will turn your Durant into a poke-shredder.
Truant: The pokémon will only perform an action once every two turns (think Slaking). This sounds like a horrible thing to have... except that Durant can use Entrainment, allowing you to foist the ability off on the enemy. Then you can switch to a pokémon that's less lazy and have a whole lot less trouble. Annoying, but less annoying than you'd think. (And it's a terrible pun to boot.) Truant is a hidden ability.
Durant has a decent repertoire of moves that reeeeally capitalizes on its high Attack score. For the most part you'll want to saddle this pokémon with attacking moves that will ravage the opponent. X-Scissor and Iron Head are your staple STAB moves, and they'll do nicely for the majority of opponents. Crunch is a decent follow-up (though not that necessary with X-Scissor around), as are Return and Dig, the latter of which will allow Durant to wipe out fire-type pokémon, the bane of its existence. I'd also recommend Aerial Ace - it will receive a hearty boost from Hustle, and you won't have to worry about missing. Last up, if you think you'll want your Durant to stall a bit, Thunder Wave is always a wise choice.
Durant also boasts a rather large repertoire of rock-type moves. These can be quite powerful, particularly Stone Edge, but they'll suffer from rather pathetic accuracy if your Durant has Hustle. Indeed, I wouldn't recommend putting any move with an accuracy below 100% on Durant. The chances of hitting are just too low. Always mould your ant with a less-than-perfect hit ratio in mind. If this is too much for you to bear, then consider using Hone Claws at the beginning of each battle to boost your accuracy.
EV / Super Training
Two words: Attack and Speed. Durant already specializes in both, and it will need every point it can get to outpace the competition. Remember, your Durant is going to be relatively frail against almost every Special Attack, and if it fails to go first it will probably die. (Change that to 'will die' if you're facing anything with a fire-type move.) OHKOs are the way to go.
Catching a Durant
Durant are fairly plentiful in Pokémon X and Y. Make your way to Terminus Cave and you'll find them all the time. You can also find them a little more rarely on Route 18, though even here all you really need to do to track down a Durant is use Sweet Scent or Honey on the grass to pull up a horde. Durant hordes are very common.
Though it's easy to catch a Durant, I recommend not using the one you catch. They appear at an unfortunately high level, and in order to optimize your ant you should start with something as low as, oh, level one. Get one and breed it with a Ditto (or, heck, another Durant) and start from there.