I added in BOTH Nidoqueen RR and Blissey PL. It made for hilarious moments.
It was my Aggrotank vs a friend's Megatank.
Meganium Prime + LandminX + E-belt dealing 100 damage to Aggron TM + 4 SPMetal + Blissey PL + Nidoqueen RR + GuardClaw! Oh noez! Then I reduced 100 damage per turn. It was quite funny to see my friend's face.
I also ran Lucian's Assignment + 4 PokeHealer+, so I could either heal my active Aggron TM or leave it with 3 normal Metals, while Lucianing the SPMetals to a benched Aggron TM. I also ran Aggron RR as a tech with Return Blow, which can become pretty handy sometimes.
However, it IS slow and the best way to set this beast up is by Skarmory UD (or CoL, but I'll be referring to UD), which unfortunately requires a Metal Energy of its own. If you draw up a SPMetal + Skarmory UD in the beginning, that knocks down Aggron's potential by a little bit.
Magnezone SF (Electric Type I think?) could help this guy out a bit, sorta acting like a Typhlosion Prime. Haven't playtested it yet, on account of my breaking down the Aggrotank.
See, the thing with Aggron TM is that...
Snipers will snipe around you. 80 damage by GuardClaw + Ebelt isn't very scary if you think about it. Even if you did use Second Strike the next turn, the sniper would probably just retreat for another sniper, or another option. For example, Garchomp C LV.X could be PokeTurned, then Lux X would be brought out and take easy KOs, thereby completely bypassing Aggron's formidable bulk.
You're easily hit by conditions, unless you run Warp Energy or Warp Point. For example, Crobat Prime, Seviper CoL, and other condition Pokemon could poison you. With a heavy 4 retreat cost, it's not really viable to discard 4 Energy (DCE + 2 SP/NonSPMetal or 4 Non/SP Metal or any combination...). PokeHealer+ could help with this, although TrainerLock would clog your hand.
Blaziken FB X just...destroys this deck. Absolutely destroys. Honestly any Fire deck would beat down this poor dude. x2 Fire Weakness is not fun. x2 Weakness to anything isn't fun in general, really.
All in all, it's a really fun deck if you can bring out Aggron's full equipment. It's just not good in this current meta. Maybe next meta, with all those whippersnapper new B/W cards.
...
Did I mention Porygon Z LVX?
*MODE CRASH!!!*
(yes, this happened to me once. Was vsing a friend's PoryZX deck. Took me 4-5 turns to set up Aggron with 4SPMetals, then BAM dude lays down PorygonZ LVX and yells MODE CRASH. Needless to say, after that, the deck Mode Crashed.)