You can’t redeem it until January
Itching to get your hands on the special event Contrary Serperior? You’ll get your chance soon, as Pokemon Get TV has revealed the process, which will require Pokemon Omega Ruby or Alpha Sapphire.
Basically, you use the code POKEMON497 in the code section and you can net your own Serperior. The catch is that it isn’t active until January 9th, 2015, though it will run until November 30th, 2015.
Pokémon Omega Ruby & Alpha Sapphire Coverage [Serebii.net]