Yeah so like Careful Sheer Force Steelix with Assault Vest and 252 EVs in SpDef and HP. Perfect IVs in HP, Atk, Def, and SpDef shouldn't be hard to get either. You'd think Sheer Force and Assault Vest are strange choices for what's basically an all around wall, but Iron Head at least gets a major boost in power, with MUCH more PP than Gyro Ball. Also while Gyro Ball can have more power, Iron Head would ALWAYS have 156 power without having to worry about facing slower opponents or setting up with Curse. Then Bulldoze for STAB I think (much more PP than Earthquake at least even if its a bit less powerful? I guess I don't HAVE to take advantage of Sheer Force) aaand I kind of just wanted Fire Fang for the coolness factor but maybe Rock Slide and Thunder Fang would be better. Crunch is there too at a boosted 104 power.
And I figure its defense is already ridiculous enough to not need any boosts via nature or EVs, so then HP and SpDef are brought up to be on pretty much on par with it. HP would be 38 points away, SpDef 28.
I'M SURE MORE COMPETITIVE PLAYERS WILL LAUGH AT ME, but at least it would be rather well rounded to use in-game.