Baton Pass some Speed onto this and you're good to go:
Ability: Sheer Force
Stats: Adamant/Careful, 252 Attack, 252 Sp.Def* or Speed*, 6 HP or Defense
Moves: Iron Tail, Bulldoze, Fire Fang, Ice Fang
Item: Life Orb (kind of a "duh" factor here with Sheer Force and 4 added effect Moves)
* These EVs are set to bolster your piddling Sp.Def to survive a random Special hit, but Speed can be used quite well with a BPassed Speed buff. Your call...
Dual STAB plus Ice Fang for Dragon Types (especially Salamence, Altaria with Cotton Guard, and Garchomp) and Fire Fang for that Ferrothorn in everyone's side. Simple Sweeping, but you'll need to have proper Baton Pass setup to get it going (Speed buffs of course, but Iron Tail needs a Hone Claws or two to bolster the low accuracy if you plan to use it). Be sure to avoid/eliminate Hazers and Phazers ASAP.
-Pranksters can wreak havoc, but need to have an Attacker as backup.
-Anything with Grass Knot can hit for a decent Neutral Hit against Steelix's low-ish Sp.Def.
-In a Wonder Room, Low Kick can obliterate Steelix (Golduck can learn both via Level Up and 4th Gen Tutor, respectively).
-Mold Breaker is the bane of Sturdy Ability. You won't get your second chance from a potential 1-shot. Fire Moves and Scald can do a similar job and weaken the Attack of your only shot (if you're really unlucky, that is). Getting in on a trap like Spikes or Stealth Rock also ruins Sturdy, of course.
-Most Special Attackers will turn the Iron Snake Pokemon into a belt with Surf, Scald, Flamethrower, Focus Blast, Earth Power, and a plethora of pain.