To get a Wynaut Egg in Pokemon X and Y breed Wobbuffet with Ditto or a Pokémon in the Amorphous Egg Group while it's is holding the Lax Incense.
You can get a Wobbuffet in Reflection Cave in Pokémon X and Y. You can also get them in the Psychic type Friend Safari, through trade or by transferring one over from B/W/B2/W2 using Pokémon Bank.
You can purchase a Lax Incense from a shop in Coumarine City in Pokémon X and Y, along with all the other Incense for 9600 Pokémon Dollars each.
Hope I helped :)