I need the ragecandybar to wake up one of those Darmanitan.
You get it from Professor Juniper but only after you beat the Elite 4 and go back to the Relic Castle in the desert.
During winter, you can go to Iccurus city and go tot he south east house, which you can finally reach and some people blabl about being former Team Rocket cronies and one of them gives you a RageCandyBar.
Also you can get one at the royal unova by defeating 6 trainers
I was just given one by a random person when I was in castelia city in the bulding right at the end street
I got it from proffesossor juniper once u beat the elite 4
Once you beat the elite four, go to the relic caslte and Proffesor Juniper talks to you about Darmanitan and how the statues are sleeping Darmanitan and gives you one so you can wake them up.