How do we take care of opposing Gengar here? I'm sure revenge killing isn't reliable considering Gengar will take out a Pokemon before you get chance to bring in your Gengar. If their Gengar has Choice Scarf, then it rules out your Jolteon's chances to get rid of it effectively.
I'm sure we can find Jolteon a replacement here. You do have some noticable defense here in Cressilia / Donphan. I'm thinking of a Rest Cressilia and Donphan with Celebi / Blissey using Heal Bell so the team's sturdeness increases drastically.
If we add Celebi over Jolteon - You have a Pokemon that will take care of Gyarados without risking the chance of the opposing Gyarados using Waterfall on your Gengar switch (with Gengar being your lead, they could find out the set pretty quickly, which will warn them that they can't sweep straight away, and they'll predict you bring in Gengar so he uses Waterfall and there goes your answer to Gyarados).
However, we could give EVs to Cressilia that looks like 252 Hp and 252 Defense with a Bold nature so Gyarados doesn't need 1 flinch on your Cressilia. This would give you room to add in Blissey over Jolteon.
Let me aide you with visual changes because there's so much we can do to give the team a better look in today's metagame.
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP/216 Def/40 SDef
Bold nature (+Def, -Atk)
- Thunder Wave / Stealth Rock
- Recover
- Heal Bell
- Grass Knot
Starmie @ Leftovers
Ability: Natural Cure
EVs: 172 HP/104 Def/216 Spd/16 SAtk
Timid nature (+Spd, -Atk)
- Ice Beam / Toxic / Thunderbolt
- Surf
- Rapid Spin
- Recover
Blissey (F) @ Leftovers
Ability: Natural Cure
EVs: 16 HP/252 Def/240 SAtk
Modest nature (+SAtk, -Atk)
- Seismic Toss / Stealth Rock
- Softboiled
- Wish
- Ice Beam
Replacing Donphan, Jolteon and Breloom.
Blissey, Gyarados, Gengar, Cressilia, Celebi and Starmie. There's one Pokemon that this team will have problems with and that's Tyranitar. Which leads me to advise this change to Cressilia:
Cresselia (F) @ Leftovers
Ability: Levitate
EVs: 252 HP/252 Def/4 SDef
Bold nature (+Def, -Atk)
- Psychic / Reflect
- Ice Beam
- Rest
- Toxic / Hidden Power [Fighting]
You can now take down Tyranitar with everything but Blissey. Even if Tyranitar will take down a certain Pokemon, you have an answer to it.
Ask questions, and I will be able to answer them for you. ^_~