Halcyon.
@Choice Specs
Nah, I feel like, for the most part, Pokémon like the ones you mentioned (Steelix, Bastiodon, Shuckle) aren't used because they have no offensive options, but rather their defensive typings leave a lot to be desired. There's also the problem of these Pokémon's speed. Most of them are so slow that they can't really make use of their offensive presence anyway. Another issue with the move itself is that it would require you to invest in both defense and attack, which would lower your overall power since you wouldn't just be able to spam a Steel or Rock type move. The only Pokémon I could see making use of this would be Metagross, which has naturally high Defense AND Attack as well as decent speed, but even then, it wouldn't like having its EVs split.