I feel that I should Answer this. Don't go crazy with the EVs as I told many users, because they aren't doing you any good. Here we go:
Cloyster:
Cloyster is terrible to be honest, you have 2 Pokemon who can set up Entry Hazards, yet you choose Cloyster? I'm recommending a Lead Sashter Moveset that has crushed many plus that is Cloyster's main niche that got him into OU in the first place:
Cloyster (M) @ Focus Sash
Trait: Skill Link
EVs: 4 HP, 252 Atk, 252 Spd
Adamant Nature (+Atk, -SAtk)
- Shell Smash
- Icicle Spear
- Rock Blast
- Razor Shell
Standard Cloyster. Shell Smash boosts your Attack and Speed to enormous levels. Icicle Spear is amazing STAB that breaks through Substitutes. Rock Blast is nice coverage that works well with Skill Link. Razor Shell is alternative STAB that does heavy Damage to Steel Types. Beware of Priority Users and Jirachi, because there is no way you'll beat them.
Chansey:
Chansey is pretty bad, mainly the EVs because you invested in Attack EVs yet you aren't using them. Also, Chansey isn't going to survive a Physical Hit, so Counter is a waste of a moveslot. I recommend Wall Chansey for your Team:
Chansey (F) @ Eviolite
Trait: Natural Cure
EVs: 252 HP, 248 SDef, 8 Speed
Calm Nature (+SDef, -Atk)
- Wish
- Toxic
- Heal Bell
- Seismic Toss
Cleric Chansey at your service. Wish Heals and heals your Team Members. Toxic cripples opposing Sweepers and Walls really well. Heal Bell gets rid of Status in your Team in one Turn. Seismic Toss is constant 100 Damage to the opponents Pokemon, which is really nice. The EVs let it outspeed other Blissey, while maintaining your Wall status.
Chandelure:
Honestly, Chandelure seems out of place in this Team, since you have Heatran supporting Ferrothorn. So, I recommend replacing it for:
Gengar
Gengar can take Fighting and Ground Type hits for Chansey, Ferrothorn, and Heatran(Ground). While they can Take Ghost Type hits for Gengar. Here is what I recommend:
Gengar (M) @ Black Sludge
Trait: Levitate
EVs: 4 HP, 252 SAtk, 252 Spd
Timid Nature (+Spd, -Atk)
- Substitute
- Shadow Ball
- Focus Blast
- Energy Ball
Sweeper Gengar here. Gengar Supports your Team by taking Fighting Type hits and Ground Type hits (Heatran). Substitute is there if you can predict your opponent switching out, Shadow Ball is STAB . Focus Blast covers Steel and Normal Types that Wall Gendarmes. Energy Ball has nice coverage towards Ground Types, so that is a must here. Gengar supports the Team way more than Chandelure, so I really recommend switching it for Gengar.
Will finish accordingly.
-Mike