Ferrothorn - I would change Rocky Helmet to Leftovers but that is your call. Leftovers + Leech Seed is extremely trolly, and although I know Rocky Helmet + Iron Barbs is as well, Leftovers is better IMO.
I'm afraid Kyurem-B no longer fits on the team due to his Fighting weakness, as the changes I will be making will require his leaving. As a replacement, I am going to give you another physical sweeper that can singehandedly 6-0 opposition after just one turn of set up.
Gyarados - Even though this guy prefers Rain he is a beast in Sand, yes I said sand. When I'm done this is gonna be a sand team. Anyway, after but on Dragon Dance Gyarados is an absolute MONSTER, and with 2 DD's up, the other guy will probably RQ.
Gyarados @ Leftovers/Water Gem
EVs: 252 Atk / 4 Def / 252 Spd
Jolly Nature (+Spd, -SAtk)
- Dragon Dance
- Ice Fang
Now I know that Elemental Gems are usually a bad idea, but I have found that MoxieDos can actually use a Water Gem very efectively, as it boosts his only STAB move on the set, helping to pull off the initial KO you need to get your Moxie Boost and start a sweep. If you don't like the Gem idea you can always go lo Leftovers, which will cancel out sand damage. Dragon Dance gets you up to super-sweepiness and usually you only need one, especially if you are running Water Gem. Waterfall is STAB and hits like runaway train, while EQ and Ice Fang are coverage.
Reinuclus - CM Reuniclus is a huge threat to most anything, but you need to make it more defensive. Run 252 HP / 196 Def / 60 SAtk and change Leftovers for Life Orb. Next, ditch HP Fire for Recover, and put Focus Blast over Psyshock. It is nice to have STAB but you need maximum coverage and Shadow Ball + Focus Blast give nealry perfect coverage.
Gengar - Looks great, the only thing I would do is give it Disable instead of Energy Ball, as SubDisable Gengar can troll really hard as well as sweep, and is suprisingly hard to take down.
Landorus-T - Looks absolutely great but I suggest you change his Band to a Scarf for some late-game chaos and the ability to revenge kill like a boss.
Say goodbye to Deoxys because CB Tyranitar is now your 6th pokemon :D
Tyranitar - From the 2 Choice Bands you had at the beginning I got the message you wanted a CB abuser, and T-tar can benefit the team by trapping, punishing opposition on the switch, and setting/keeping sand up.
Tyranitar @ Choice Band
Trait: Sand Stream
EVs: 180 HP / 252 Atk / 76 Spd
Adamant Nature (+Atk, -SAtk)
- Stone Edge
- Crunch/Fire Punch
With a Choice Band Ttar is at 604 Atk, and that is nothing to screw around with. Stone Edge is your main STAB and absolutely punishes most anything that isn't KO'd. Pursuit is for trapping enemies and is extremely convenient, an almost must-have. Crunch is secondary STAB and more reliable than Stone Edge, but Fire Punch is an option to take down Ferrothorn, Scizor, Forretress, etc. Ttar synergizes extremely well with your other team mates, Gengar especially.