For those who want japanese decklists, here's a tip:
You can google 【デッキレシピ】 + the japanese name of a Pokémon from the deck you're looking for (e.g. Hydreigon, Eelektrik, Garchomp, etc.). (You can find a Pokémon's japanese name on Bulbapedia for example).
This gives lots of decklists in japanese blogs, though obviously you'll need a translator to read them. It's not a perfect method to get the best decks, since you don't know whether the lists you find had success, whether they're popular, etc. You can try to read comments and all but once again, it's in japanese.
Still, I found this to be quite useful to get an idea of Japanese decks.
To give credit where credit's due, this tip comes from an anonymous comment on an article from The Deck Out.