Pikachu wearing Ash’s hat distribution announced for Pokémon Sun and Moon in Japan

Various Pikachu wearing Ash‘s hat have been confirmed as a special Pokémon Sun and Moon distribution for those who prebook tickets to Pokémon the Movie: I Choose You! in Japan. Those who do so will receive one serial code that comes with the special Pikashumium Z Crystal, which activates the special Z-Move called 10,000,000 Volt Thunderbolt.

Original Cap can be obtained from April 15 to May 1 and then from July 19 to July 31
Hoenn Cap from May 3 through May 15 then again from August 2 through August 14
Sinnoh Cap from May 17 to May 29 with a repeat on August 16 through August 28
From May 31 through June 12 you can get the Unova Cap, repeated on August 30 through September 11
From June 14 through June 26 you can get the Kalos Cap, repeated September 13 through 25
Finally, from June 28 to July 17 you can get the Alola Cap Pikachu, repeated from September 27 through October 9

A pre-booking ticket serial code can be redeemed only once.

Source: Serebii