Sylveon is the newest out of the Eeveelution bunch and new type and yeah yeah...Sylveon isnt my most favorite other than it being my 2nd favorite fairy type while the other being Xerneas (Bambi's mom) but anyway on to the moveset part.
Item: Quick Claw (to help you attack first)
Ability: Cute Charm
Nature: Modest,Calm -Bold.-
EVs: 252 Sp.Atk, 252 Sp.Def and 4 HP
-Hidden Power (Steel)
Moonblast will gain STAB and has great power, With this hidden power (if you got the right sylveon) you have great coverage, Calm Mind powers up Sp.Atk and Sp.Def so keep useing it to make Moon Blast and Hidden Power Steel and great bulk plus you can baton pass it, With Cute Charm you can cripple your foes (if they are the opposite gender of sylveon) wich will give you sometimes a chance to use power ups and with Modest your two offensive moves will be powered up or if you use Calm you get a bit bulkier with Sp.def and if you really want your defense boost then have no fear Bold is here