Question

How to get Genesect on X and Y?

Answer 1

No, unfortunately not.

Genesect is like most other event legendaries - they are only available as an event Pokemon in their corresponding generation. So, you could have only gotten Genesect has an event Pokemon from Gen V.

Of course, if you had Genesect, once the PokeTransfer is available you can transfer it to X and Y.

Hope I helped. :)
Source

Answer 2

You cannot get a Genesect in game in Pokémon X and Y.

The only way to get a Genesect in your Pokémon X or Y game is by trading for one, or by transferring one over from Pokémon Black, White, Black 2 or White 2 using Pokémon Bank.

Source: http://bulbapedia.bulbagarden.net/wiki/Genesect_(Pokémon)

Hope I helped :)

Answer 3

You need to trade with someone from Black or White and get a Genesect from them