Ridiculously Defensive Fire/Steel

[Richard and Blaziken]

Be careful not to give it too much. This looks like a legendary, so no Egg moves in my opinion. Here's how I'd lay it out:

-Fire Fang
-Smokescreen
-Withdraw
8 - Ember
12 - Metal Claw
18 - Ancientpower
24 - Metal Sound
30 - Will-o-Wisp
36 - Iron Defense
42 - Roar
47 - Lava Plume
50 - Iron Head
58 - Stone Edge
65 - Fire Blast
71 - Head Smash
80 - Flash Cannon
88 - Eruption

TMs:
TM01 - Hone Claws
TM02 - Dragon Claw
TM05 - Roar
TM06 - Toxic
TM10 - Hidden Power
TM11 - Sunny Day
TM12 - Taunt
TM15 - Hyper Beam
TM17 - Protect
TM20 - Safeguard
TM21 - Frustration
TM22 - Solarbeam
TM23 - Smack Down
TM26 - Earthquake
TM27 - Return
TM28 - Dig
TM32 - Double Team
TM35 - Flamethrower
TM38 - Fire Blast
TM39 - Rock Tomb
TM42 - Facade
TM43 - Flame Charge
TM44 - Rest
TM45 - Attract (Unless this Pokemon is genderless. Keep in mind, some legendaries are, some are not, but if it is, it has to learn Attract via TM)
TM48 - Round
TM50 - Overheat
TM54 - False Swipe
TM59 - Incinerate
TM61 - Will-o-Wisp
TM65 - Shadow Claw
TM66 - Payback
TM67 - Retaliate
TM68 - Giga Impact
TM70 - Flash
TM71 - Stone Edge
TM74 - Gyro Ball
TM78 - Bulldoze
TM80 - Rock Slide
TM87 - Swagger
TM90 - Substitute
TM91 - Flash Cannon
TM94 - Rock Smash
HM04 - Strength

Move Tutors
-Iron Head
-Iron Defense
-Iron Tail
-Snore
-Sleep Talk
-Stealth Rock
-Earth Power
-Heat Wave
-Knock Off
-Pain Split

In my opinion, these are the moves that make the most sense with the design without making it overpowered. I'm not saying it's the end-all list or anything, just my opinion on it.

[quack98]

That looks good, but there's one possible flaw, I'm assuming they'd all have a Lv. 88 move similar to eruption. If it the Water or Ice one was Water/Steel, then Water Spout would be the obvious choice, but then what for the electric one? The only options I can think of there would be make a new move, or use Volt Tackle (or another similar move I'm likely overlooking)

[Spriter]

I think maybe adding molten iron panels to the sides of its head would look cool, but great designs overall!

If this were to be standard in OU, it's set could be

- Stealth Rock
- Toxic
- Dragon Tail
- Morning Sun/Rapid Spin

That looks like something a Sun Team would love. A more defensive Heatran that can phaze and spin? Hell yeah.

I think it should have a move pool like Torkoal, as all bar Dragon Tail are in it's move pool iirc.

Holy smokes (no pun intended) Rich, thst was ninjaesque

[Richard and Blaziken]

Thunder would work as the final move for an Electric/Steel type. It's not perfect, but neither is Eruption. In fact, on this, it's nearly useless.

As for Rapid Spin and Dragon Tail, they seem a bit iffy to me. Dragon Tail seems a bit too OP with such a defensive Pokemon that can inflict status in so many ways without being able to be worn down by Toxic/Toxic Spikes. It also doesn't really have a Dragon-esque tail, in my opinion. Similarly, Rapid Spin seems... odd for a legendary, and on something this defensive, it'd make Spinning incredibly easy, which seems to be something that they shy away from.

And finally, I think giving it any recovery move outside of Rest and Pain Split would be enough to break this Pokemon, even if it is weather reliant.

Given the moves I've listed, I could see the following two sets being viable:

Rest, Sleep Talk, Lava Plume, Toxic

Stealth Rock, Lava Plume, Toxic/Will-o-Wisp, Pain Split / Flash Cannon / Hidden Power (Grass/Ice)

[quack98]

Thunder would work as the final move for an Electric/Steel type. It's not perfect, but neither is Eruption. In fact, on this, it's nearly useless..

Ah, I was assuming that to be the Fire Blast counterpart, but if it isn't, Thunder would work fine.

Edit: Just out of boredom, I ran a quick calculation into PS's damage calculator, and 252 Adamant Salamence is guaranteed to 2HKO a 252/252 +Def one of these with Earthquake (assuming Solid Rock)

[NTN]

Shell Armor is another possible ability. If this is so defensive, the ability blocks critical hits and makes it even more so. It's probably overshadowed by some other possible abilities here, but this ability's name is even connotative of the Pokémon's Steel typing.

[quack98]

Just to add to what SiteHaunter said, it would also open a possibility to use defense boosting moves. Although they may not have room on the sets, it still becomes much more plausible if crits aren't going to ignore them.

[Spriter]

Disallowing crits is a bit OP, but considering that calculation, maybe it has merit? Registeel has similar defensive stats, so possibly looking at that might provide more ideas.