ORAS OU Tanky team around Ferrothorn

[Bzoka]

Before I get told off, know that I'm pretty new with competitive battling. "Inexperienced" would be a better word, and I don't have enough knowledge about it to make huge, 5-6 line assessments about each Pokemon. I'm looking to learn, and help would be appreciated. With that said, I've seen your format closely and I think I kept to it (apart from the explanations being tiny).

Ferrothorn @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 88 Def / 168 SpD
Nature: Relaxed
-Stealth Rock
-Leech Seed
-Power Whip
-Thunder Wave

Reason: Obvious set up and stall. The team was built around Ferrothorn.


Rhyperior @ Leftovers
Ability: Solid Rock
EVs: 212 HP / 44 Atk / 252 Def
Adamant Nature
- Earthquake
- Stone Edge
- Ice Punch
- Stealth Rock / Fire Punch

Reason: To check birds, especially Charizard and Talonflame.


Blissey Leftovers
Ability: Natural Cure
252 HP/4 Def/252 SpD
Nature: Calm
-Protect
-Soft Boiled
-Toxic
-Seismic Toss

Reason: Special wall and scout.


Gourgeist (Small) Leftovers
Ability: Frisk
EVs: 252 HP/208 Def/48 Spd
Nature: Calm
-Leech Seed
-Substitute
-Fire Blast
-Will O Wisp

Reason: To take out/check rapid spinners. Decent wall.


Conkeldurr @ Assault Vest
Ability: Guts
EVs: 4 HP / 252 Atk / 252 SpD
Adamant Nature
-Knock Off
-Drain Punch
-Ice Punch
-Mach Punch

Reason: Threat to Magnezone, to save Ferrothorn’s ass. Makes for some offense in a tanky team.


Charizard Charizardite X
Ability: Blaze
144 HP/252 Atk/112 Spe
Nature: Adamant
-Dragon Dance
-Dragon Claw
-Flare Blitz
-Roost

Reason: Set up, sweep.


What flaws do you see? Which Pokemon could be serious threats to my team? Could I make some changes, or is the entire team garbage? Thanks!

 

[Alfalfa]

You could start by moving all of Blissey's HP EVs to Defense and running a Bold Nature. This allows Blissey to actually live a physical hit so you do not get calcs like these:

0 Atk Ferrothorn Power Whip vs. 252 HP / 0 Def Blissey: 516-607 (72.2 - 85%) -- guaranteed 2HKO
252 SpA Life Orb Latios Psyshock vs. 252 HP / 0 Def Blissey: 715-842 (100.1 - 117.9%) -- guaranteed OHKO

But rather, calcs like these instead:
252 SpA Life Orb Latios Psyshock vs. 4 HP / 252+ Def Blissey: 308-364 (47.2 - 55.8%) -- 79.3% chance to 2HKO
0 Atk Ferrothorn Power Whip vs. 4 HP / 252+ Def Blissey: 222-262 (34 - 40.1%) -- guaranteed 3HKO

While Blissey is meant to be a special wall, being unable to take any physical attack just means Blissey will automatically lose to any Psyshock user or any wall carrying a moderately-strong physical attack.