The Code for the Ash Cap Pikachu is
At first this was confirmed for NA games only, but apparently it should work for PAL as well?
Please get on mystery gift and let me know!
Edit: IMPORTANT The date you redeem it affects which pikachu you will get!
9/19/17 – 9/25/17: Original hat (Kanto and Johto regions)
9/26/17 – 10/2/17: Hoenn region hat
10/3/17 – 10/9/17: Sinnoh region hat
10/10/17 – 10/16/17: Unova region hat
10/17/17 – 10/23/17: Kalos region hat
10/24/17 – 10/30/17: Alola region hat