Overview: steelix use to be THE WALL as in their use to be steelbiss(Steelx and blissy combo) which was removed for skarmbliss
Stats
75 HP...Not to bad its usable
85 ATK...Again not to bad
200 DEF...GODLY DEFENSE
55 SP.ATK...its not like your gonna use sp.atk right?
65 SP.DEF...Bad...it made steely RU
30 SPE... Actually...really good for gyro ball

Sets
Offensive Item:Life orb/Left overs EV's 252 ATK 252 HP 4 sp.def Nature:Brave Ability:sheer force
-Rock slide IV's 0 speed
-Earthquake/Crunch/Bulldoze
-Curse
-Gyro ball
This is a unusal set but it takes advantage of cheer force-life orb combo being able to do loads of damage...in theory at least

Standard wall Item:Left overs/Chesto berry EV's 252 HP 252 Sp.DEF 4 DEF Nature: Sassy Ability sturdy
-Curse IV's 0 Speed
-Rest
-Gyro ball
-Explosion/Dragon tail/Toxic
Kinda the basic set curse up and be come nearly un-killable

Support Item:Left overs/Passho berry/Occa berry/Shuca berry EV's 200 52 DEF HP 252 SP.DEF Nature: Sassy Ability sturdy
-Stealth rocks IV's 0 Speed
-Dragon tail
-Subistute
-Gyro ball

Opinion
Steelix is a "solid" poke crazy defense 11 resistance's And has quite a bit of nifty support moves such as Stealth rocks,Dragon tail,Torment,Taunt and roar all-in-all a great RU poke

What coulda been
really...it just needs special defense thats its only real draw back

Other options
Double edge could be used on a rock head set sadly he lacks head smash rock head combo that made aggron such a threat in RU A taunt set could annoy dusclops and manget rise can be pretty useful

Any feed back will be appreciated
~Darkanine