Normal Gem Explosion Metagross could work as an anti-anything 'mon, I guess. Unless said anything carries Protect/Detect/Wide Guard, or is a Ghost-type.
I guess Normalize Delcatty could use Normal Gem as well. Boost to any move it desires, on the first turn at least. Pair it up with Covet to annoy opponents. That is, until they realize they're facing a Delcatty and promptly KOs it with... well, that doesn't really matter.