Did you get Gensect within your gamebox?

My pokemon black 2 pal version (EU) didn't have a code, so where do I get one?Did I miss it?

Yes you have missed it you needed to connect to the Wi-Fi mystery gift part of the menu within the first month of release to get a genesect.

It was a reward for people who bought the game at launch.

There's an explanation in the game case