Pokémon X and Y Walkthrough, Pokémon Move Sets: Slurpuff
(Please note that the recommendations below are largely made for in-game play. A Slurpuff in a competitive environment will likely make use of different moves to accommodate for smarter, more adaptive opponents. Have a different set of moves for Slurpuff? Let us all know in the comments.)
Slurpuff. Is it a dog? A puffed pastry? Both? Either way, this is one derpy-looking and altogether strange pokémon. A newcomer with the sixth generation, as well as one of the first all-new fairy-type pokémon, Slurpuff is an addition to your team which will take some getting used to... but once you figure out its niche, Slurpuff can prove to be quite a useful partner.
Slurpuff begins life as a Swirlix, and, sadly, it's another of those annoying trading pokémon. To get a Slurpuff you'll have to trade a Swirlix with a Whipped Dream attached. It will immediately evolve into a Slurpuff in the aftermath.
Bug, Dark, Fighting. Immune to Dragon.
Slurpuff is the epitome of 'average'. Its stats are all extremely close to one another: HP is good, Attack is good, Defense is good, Special Attack is good, Special Defense is not quite as good but still isn't bad, and Speed, though coming in last, is still serviceable. Unfortunately, this also means that, at least statistically, Slurpuff doesn't stand out at all. You could take it any number of directions... or you could opt for a different, more specialized pokémon instead. Fortunately, it's saved by its moves.
Sweet Veil: Moves that put a pokémon to sleep will not work on Slurpuff. These moves also won't work on other pokémon in your team. This ability can be a blessing or a curse, depending on your team, as it prevents Rest from working. If one of your pokémon relies on Rest (poor Snorlax), Slurpuff is a teeeeeerrible addition to your team.
Unburden: If a pokémon loses its held item during a battle, its Speed is immediately doubled. A fantastic ability if you like to use berries, particularly those that restore HP.
Slurpuff is a restorative pokémon, no two ways about it. It's set up to both heal and buff your team. Aromatherapy is the big move to have on this build, as it will immediately cure every pokémon on your team afflicated with a status ailment. Pretty handy. Wish is good for restoring HP with a setup and quick switch, Light Screen is great for boosting Special Defense, and Cotton Guard is good for boosting Slurpuff in general. It's also wise to take advantage of Slurpuff's typing, in which case Dazzling Gleam is your best bet.
The alternative is a Slurpuff that's a bit more dedicated to battle, which isn't a horrible idea. Dazzling Gleam remains a staple, as does the naturally-learned Energy Ball. Flamethrower and Thunderbolt are decent alternatives as well. Fill up the extra slots with a few defensive moves (Cotton Guard and Light Screen will do quite nicely) and you've got a decent attacker. Not amazing, but decent.
Last up, you can turn Slurpuff into a surprisingly good user of Toxic. Administer the poison, then use Slurpuff's defensive and healing moves to keep it alive while the competition slowly dies. Cotton Guard, Light Screen and Wish remain good choices, though in this case you shold also consider Draining Kiss, which absorbs half of the attack's damage as HP for your Slurpuff.
EV / Super Training
EV training depends on the direction you want to go, so gear your choices to your moveset. I prefer a Slurpuff with higher defenses, personally, though boost its HP isn't a bad idea either. If you go the attacking route, make sure you stick with Special Attack - Slurpuff doesn't get enough quality physical moves to warrant boosting Attack.
Catching a Slurpuff
Ah, the trading enigma. If you own Pokémon X you can find Swirlix, Slurpuff's predecessor, on Route 7. Problem is, you need to trade the Swirlix with a Whipped Dream attached to get a Slurpuff - which, given the largely-online nature of Pokémon X and Y's trading scene, means you probably won't get it back again. I advise looking for a Slurpuff online that people are willing to trade instead. This is especially easy if you have Pokémon Y, since most traders with a Slurpuff posted will want a Spritzee with a Satchet attached.