Yay, I'll answer :D
For Deoxys-D, a nice item to try is Mental Herb. This really helps when you start to Taunt and your opponent has Espeon or Xatu in their team. If you don't know what it is, a Mental Herb cures you from Confusion, Infatuation, and Taunt, mainly. Deoxys-D has the bulk and Recover to do without Leftovers. I'd also move your 4 Def EVs to SDef to stop any Downloaders from getting a SAtk boost.
Your Gengar seems fine.
Your Ferrothorn can utilize a spread of 252 HP / 88 Def / 168 SDef with an Impish Nature. This EV spread presents lots of bulk, and really helps when tanking both Dracos and Outrages.
Let's have some fun with Heatran. It seems that you are going for an offensive Heatran here, but your EVs are kind of messed up. I recommend a highly unused set.
Heatran (F) @ Life Orb
Trait: Flash Fire
EVs: 252 SAtk / 4 SDef / 252 Spd
Modest Nature (+SAtk, -Atk)
- Flame Charge
- Fire Blast
- Earth Power
- Hidden Power [Ice]
A nice and weird set to use, but perfect to catch your opponent off guard. After you switch into a Fire move, use Flame Charge on the switchin, and now, you got a Heatran that can basically outrun any non Scarfed user in OU. Fire Blast is your STAB move. COming off a 394 SAtk stat, STAB, and LO? Earth Power nails opposing Heatran for the OHKO. Hidden Power Ice laughs at all those Dragons that think they can resist you.
Onto your Gliscor. You have 2 Pokemon with defensive capabilities already; Ferrothorn and Deoxys-D. I suggest you swap Gliscor for Landorus-T. You retain the same typing, as well as a Defensive presence. But you get a bit more Physically offensive, which is what your team lacks. I suggest a Scarf set. Believe me, Double Scarfers work well.
Landorus-T (M) @ Choice Scarf
EVs: 20 HP / 236 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk)
- Stone Edge
Credit to thy Holy Name for the EV spread. This set is pretty darn straightforward. U-turn provides some scouting, Earthquake (STAB) and Stone Edge provide the EdgeQuake combination. Superpower gives additional power to break through Steels like Ferrothorn.
Your Kyurem-B needs a Hasty or a Naive Nature to outspeed certain threats.