Yo, /vp/

Where the fuck is the spooky plate? It says in front of a cave but there is none in Hau'oli Cemetery. http://www.serebii.net/pokearth/alola/hau'olicemetery.shtml

Also is Serebii any good in terms of what pokemon are there available in each location? I kinda like collecting everything I can get while I play the game.