Sacred Sword is the preferred option over Iron Head because Ghost/Fighting is unresisted coverage. Of course, Iron Head is still useful for hitting Fairies hard without resorting to a weak Shadow Sneak.
I don't like the way Jellicent's set is presented. Substitute only sees use for scouting opponents' moves, and Jellicent isn't built to scout. It's built to spin block and check/counter the types it's strong against. Lax is a terrible nature competitively because it doesn't benefit Jellicent in any way by hindering its good Special Defense:
-Scald/Shadow Ball/Night Shade
-Will-o-Wisp/Toxic
-Recover
-Taunt
Nature: Bold
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
or
-Scald/Surf
-Shadow Ball/Ice Beam
-Will-o-Wisp
-Recover
Nature: Calm
EVs: 248 HP/36 Def/224 SDef
Item: Leftovers
Ability: Water Absorb
or
-Water Spout
-Hydro Pump/Surf/Scald
-Shadow Ball
-Ice Beam/Giga Drain
Nature: Modest
EVs: 172 HP/252 SAtk/84 Spe
Item: Choice Specs
Ability: Water Absorb
What's the point of Skarmory using a Jolly nature when its Speed isn't invested in at all? Use Impish or Careful, as either one increases its defensive capabilities:
-Spikes/Stealth Rock
-Roost
-Whirlwind
-Defog/Brave Bird
Nature: Impish/Careful
EVs: 252 HP/252 Def/4 SDef or 252 HP/4 Def/252 SDef
Item: Leftovers/Shed Shell/Rocky Helmet
Ability: Sturdy
Ferrothorn also doesn't look like a good Sub user either. It's meant to check bulky Water Pokemon. If I were you, I'd use Ferrothorn + Jellicent, as they cover each other's weaknesses quite nicely:
-Stealth Rock/Spikes
-Leech Seed
-Gyro Ball/Thunder Wave
-Power Whip/Protect
Nature: Relaxed
EVs: 252 HP/208 Def/48 SDef
Item: Leftovers/Shed Shell
Ability: Iron Barbs
Jolly is preferred for Scarf Tyranitar, as Adamant Tyranitar is still slow, even with Choice Scarf.
I'd use Blissey for the ability to heal itself with Leftovers passively, as Chansey gets worn down easily, even with Soft-Boiled.