Lets put this back into perspective. 85 base STAB vs 110 base STAB.
I wasn't saying Steelix's EQ was more powerful than Aggron's Stone Edge, just more useful and more reliable.
Thats a rather big difference and Iron Tail could hardly be considered best anything, maybe best at missing completely.
I was talking about Gyro Ball, which given Steelix's crap speed, can easily reach the power of Iron Head and even move up to Close Combat power against things like Pinsir and Froslass.
I really need to save the formula for GB somewhere. IIRC:
Power = Opponents Speed * 25/Your Speed
Steelix goes down to 58, so:
Power = Opponent's Speed * 25/58
Power = Opponent's Speed * 0.43.
So if we wanted 150 power:
Opponent's Speed = (Max Speed Neutral nature/Positive nature)[Floor of speed]
150 = 349 (Base 130/110)
140 = 326 (Base 115/100)
120 = 279 (Base 90/80)
110 = 256 (Base 80/70) [110]
100(IT) = 233 (Base 70/60) [100]
90 = 210 (Base 60/50) [90]
80(IH) = 187 (Base 45/40) [76]
So, while you'll only see 150 power on Froslass, Anything in the Jolly Pinsir range gets smacks for 120 power, and +Speed Base 100s get smacked with Overheat level power. I included the floors of pokemon who have a neutral speed nature. Gyro Ball will always have at least that much BP on those pokemon. (Incidentely, this is why Gengar is no longer a good switchin on Steelix, or at least not my EQ/GB/SR/Roar one.)
So I stand by my statement. Steelix has the most powerful Steel attack after Metagross.
I submit the lower numbers aren't relevant because slower pokemon won't max speed, and since most of the slower ones in UU are weak to Earthquake, it hardly matters.
Against what? Rock/Fighting? Rock/Ground? Ice/Ground, Ghost/Fighting, Water/Ground? It'd take a very brave person to dream of running a full defensive Aggron against potential threats like those with 4x weakneses. If I saw an Aggron switching in on any physical attacker I had I'd probably be like "FREE KO!"
No one would run Max Def on Aggron. Like Steelix, its defense is so high that a nature gives you something in the area of 36-40 defense points, so just leave it at that, Max HP, and distribute to offensive stats or special defense as you please. Aggrons primary defensive walling was against the CB Birds in Advance, who couldn't beat it unless they outpridicted with HP Ground or HP Fite. Now that that isn't an option, Aggron walls the hell out of Normal/Flying types in UU. Normal and Flying resists were important then, and Aggron filled that role quite well. Subbing Aggron also walls physical Ghosts like Sableye and Banette, although now that they all have WoW it needs Sub not to get burned, so to speak. For most of the physical bugs it also walls them, but in the case of Scyther it really has to tank by wiping it out with RS or SE after eating a Brick Break.
But Aggron isn't that great at taking special attacks either, not without a Sandstorm Boost, and Probopass does that better. Basically the purpose for most Aggron maxing HP was to switch in on Ice Beam or Psychic multiple times and then force the opponent out with a physical threat.
The thing is though, that Steelix can do the exact same thing, and has the added bonus of actually being able to take an EQ or CC (either) if it's forced to.