I have been at the National Championship in Denmark and Italy, where I went through every single deck list and created these Tables:
Denmark: (Counter Clockwise)
As you can see, Night March is not just the most successful deck, but also the most played deck at most National Championships, followed by Trevenant.
The high amount of Manectric in Denmark was kind of weird, and Water Box was not that established back then. In Italy we saw a Meta game as expected, most Night March and Trevenant (being the easier to play decks and are very consistent), followed by Greninja and Water Toolbox.