Alright, I have used a couple of mono-Steel teams, so I will have a go at rating this.
Your team is rather well put together, but I do have 1 overarching criticism. You have too many Steel type attacks - 3 pokemon with Iron Head and 2 with Flash Cannon. Yes, Steel moves are obviously STAB on these pokemon, but having every pokemon with them means you miss out some badly needed coverage moves. For example, if you can up against an opposing Skarmory (they are rather common on both mono-Flying and mono-Steel teams) Heatran is the only thing that could really deal with it. It would wall most of your other pokemon. I'm not saying get rid of every Steel type move, but you might want to consider getting rid of some of them.
With that out of the way, on with the team in question.
Skarmory
A good move set, although consider replacing Pursuit with Brave Bird. You have roost to heal back the recoil anyway, and I think the extra power is necessary. Also Whirlwind is better than Roar. That might seem like a small difference, but Soundproof blocks Roar, whereas the only things that blocks whirlwind are Suction Cups and Ingrain, which stop Roar as well.
The Quick Claw is not a good item competitively. I suggest Leftovers instead. I think your EVs could be better as well. Skarmory is meant to be a very defensive pokemon, especially with the move set you have given it. Its main purpose is not to outspeed, or to hit hard. So I think
252 HP/252 Def/4 Atk is better.
Heatran
A very good pokemon for any mono-Steel team. Instead of Flash Cannon, I suggest going with Will-o-Wisp to shut down physical attackers, and none of your pokemon has any status moves. Dark Pulse is also an option, but HP Ice has better coverage, so you will probably want to leave it like it is.
Aegislash
While the Weakness Policy is very good on it, I am not fond of the Special Attacking variant, simply because it has a major lack of coverage options. I see why you have used it, though, because Heatran is your only other Special Attacker. So I have several options to recommend here:
1) Keep it as it is, but replace Substitute for Autotomize. I think the extra Speed is more helpful, because of the lack of priority on this set. Or you could give it Shadow Sneak and use it as a mixed attacker, I suppose, but you would probably want to change its Nature if you did this (Quiet is probably the best option).
2) Change it to the physical variant. This is the worst option I think, simply because you already have 3 physical attackers as it is, so you don't need another one.
3) Change it to another pokemon entirely. I think this is the best option. Try Magnezone.
Magnezone @ Air Balloon/Life Orb/Choice Scarf
Ability: Magnet Pull/Sturdy
EVs: 252 HP/252 SAtk/4 SDef
Nature: Modest
Moves:
- Thunderbolt
- Volt Switch
- HP Fire
- Flash Cannon
Bisharp
This is a good pokemon. I understand why you have both Sucker Punch and Knock Off on the same move set, as both are very useful in different siutations. However, in terms of coverage I suggest replacing one of them (probably Knock Off) with Brick Break.
That is if you want to stick with Bisharp, but as you may notice its move set is very similar to Mawile. So here is an alternative option if you want something a bit different: Bronzong.
Bronzong @ Light Clay
Ability: Levitate
EVs: 252 HP/252 SDef/4 Atk
Nature: Careful
Moves:
- Light Screen
- Reflect
- Zen Headbutt
- Toxic/Stealth Rock
I have made him specially defensive to complement the physically defensive Skarmory. It is pretty much a dual screener. Zen Headbutt is his attacking move. The last option is probably going to be Toxic, as Skarmory already has Stealth Rocks. It is an option to consider, anyway. It also gives you another Ground immunity.
Mawile
This is another very good pokemon. Since it is so slow anyway, I suggest having an EV spread of 252 HP/252 Atk/4 Spd. This allows Mawile to take more hits, as it won't be out speeding much, anyway.
As for its moves, again you have both Sucker Punch and Knock Off, and again I understand why. Either get rid of Knock Off or Iron Head (because of the number of Steel attacks on this team), and go with Ice Punch for coverage.
Excadrill
Replace Aerial Ace with Poison Jab, to give you a good answer for Fairy pokemon. The low power of Aerial Ace means it is not really worth using.
I hope that helped.
