Ferrothorn should use 252 HP/208 Def/48 SDef, as it tends to switch in on a lot of physical threats. Also, pick between either Power Whip and Protect and drop one of them for Gyro Ball or Thunder Wave, the former as a secondary STAB and the latter to act as extra support.
What purpose does the 56 Special Attack EVs serve? Do they achieve notable KOs with Flamethrower? I don't think so. Blissey is too offensively weak anyway, so just use 4 HP/252 Def/252 SDef. With your current spread, Blissey may be 2HKOed by special attacks that it should be walling in the first place.
Trevenant uses 80 Speed EVs, which allows it to outspeed 0 Speed Scizor and Vaporeon. That's still not enough to outspeed 0 Speed Skarmory. For Skarmory, just use 224 HP/252 Def/32 SDef. Also, Stealth Rock isn't available till Poke Bank.
Small Size Gourgeist should take advantage of its high Speed for a wall to support the team. Your current EV spread is inefficient:
-Will-o-Wisp
-Leech Seed
-Protect/Pain Split
-Seed Bomb/Substitute
Nature: Jolly
EVs: 252 HP/72 Def/184 Spe
Item: Leftovers
Ability: Frisk
I'll test out the Ferrothron to see if it works. I have 56 evs to ensure that I can 2HKO Ferrothrons and Scizors, I might use ice beam/thunderbolt/Shadow ball however.
I can't see how useful Treventant would be as it seems to be too slow for my team.
I'll test the spread out, how is pain split good if I have max hp?
Couple of minor comments on your team:
1) Your Skarmory is such Taunt bait. It'd be best to give it Brave Bird or even Steel Wing so it'd doesn't get Taunted all day long. It'd be best to drop its own Taunt.
2) I question the usefulness of Roar on Vaporeon. I think it should use Toxic instead. Toxic is good on stall teams. I use a Vaporeon very simliar to the one you have, and Toxic+Wish+Protect works wonders. Besides, you have Skarmory already to do the entry hazards+Whirlwind thing.
3) If possible, get a bigger Gourgeist. Bigger ones have more HP, which will be helpful with stalling. Sure, you lose some speed, but you are doing stall and have Shadow Sneak on it, so you don't need Speed.
Without taunt, I am unable to stop Jellicent (In Pokebank) from burning me, and also top Blissey from healing.
Roar is good when Talonflame come in (She can't deal with banded ones) and then they switch out.
I like the idea of fast burns and seeds. I feel that the super sized one would be a bad thing for my team.