Ghost is my favorite type cos spooky scary things in a children's game. Helps that Chandelure and Froslass, my two favorite pokes, are of the type as well.
Yes, back when Rock wasn't completely undesirable. Lately everyone has ground moves and that means Rock is in a terrible position. Anyway, in the game with the ghost that had the gems for eyes, I taught him Toxic, Dig, Fly, and Protect. Basically he just stalled while Toxic's increasing damage began to build up.
Sableye in Ruby/Sapphire/Emerald and the good ol tactic of Toxic stalling. Still a relevant method with some Pokes like Umbreon, though it has lost a bit of favor since the introduction of the fairy type and the relevance it has given to poison-types.