That's true. Yurlungur is a fairly relaxed Arbok when he's outside of battle, but I don't let him slack off when it comes time to train. And grass types are weak against bug types as well, and I have a pair of bug/flying types that I'm raising for breeding that should clean them up just fine. And if all else fails... Spiritomb only have the one weakness, and mine is already at the maximum level.