Psycho Killer

[tinyranitar]

Special sweeping team
Volbeat (M) @ Focus Sash
Traits: Prankster
Evs: 252 HP / 128 Def / 128 SDef
Bold Nature (+Def, -Atk)
- Tail Glow
- Baton Pass
- Bug Buzz
- Thunder Wave

Latios (M) @ Leftovers
Traits: Leviate
Evs: 4 HP / 252 SAtk / 252 Spe
Timid Nature (+Spe, -Atk)
- Surf
- Dragon Pulse
- Thunderbolt
- Hidden Power [Fire]

Cloyster (M) @ Focus Sash
Traits: Skill Link
Evs: 252 Atk / 4 SAtk / 252 Spe
Naive Nature (+Spe, -SDef)
- Shell Smash
- Icicle Spear
- Hydro Pump
- Rock Blast

Espeon (M) @ Leftovers
Traits: Magic Bounce
Evs: 172 HP / 84 SAtk / 252 Spe
Timid Nature (+Spe, -Atk)
- Stored Power
- Calm Mind
- Baton Pass
- Hidden Power [Fighting]

Gorebyss (M) @ Focus Sash
Traits: Hydration
Evs: 128 HP / 188 SAtk / 192 Spe
Timid Nature (+Spe, -SAtk)
- Shell Smash
- Surf 
- Baton Pass
- Ice Beam

Heatran (M) @ Air Ballon
Traits: Flash Fire
Evs: 4 HP / 252 SAtk / 252 Spe
Timid Nature (+Spe, -Atk)
- Fire Blast
- Earth Power
- Dragon Pulse
- Hidden Power [Grass]

 

[PlatinumDude]

Encore needs to be somewhere on Volbeat, preferably over Bug Buzz (even though this leaves it prone to Taunt, Volbeat is too weak to take advantage of the boost itself anyway).

Latios doesn't need the Focus Sash; it's really not that frail. Give it a Choice item (Specs or Scarf). Replace Dragon Pulse with Draco Meteor, and Recover for Trick if you choose to go that way. Or, if you want to keep your set, use Life Orb instead.

Hasty wastes away Cloyster's incredible Defense pre-Shell Smash; use a Naive nature instead (which lowers its Special Defense, which is terrible already).

Espeon is better off with a speedy/bulky spread of 252 HP/4 SAtk/252 Spe. Your current EV spread is wasting away its excellent 110 Speed.

For Heatran, you can consider Stealth Rock over Dragon Pulse or Hidden Power (Grass) to support the team further

Right now, your current team is struggling against Chansey and Blissey because most of your Pokemon are using Special attacks exclusively (even with a boost, your Pokemon still have a hard time with them). Mienshao is a good counter to both. Not only that, it also has the ability to Baton Pass. If you choose to use Mienshao, you'll have to give up Gorebyss because Volbeat and Espeon are already BP'ing Special Attack boosts. Espeon and Volbeat can also BP their Special Attack boosts to it to power up Hidden Power (Ice); Mienshao's Attack is also high enough to cause severe damage with Hi Jump Kick, assuming it connects:
-Substitute
-Baton Pass
-Hi Jump Kick
-Hidden Power (Ice)
Nature: Hasty/Naive
EVs: 252 Atk/32 SAtk/224 Spe
Item: Leftovers
Ability: Regenerator

 

[Hikamaru]

Volbeat is very terrible, don't use it cos it's very frail.

For a nice Pokemon to replace it, I recommend Scizor instead cos it has very little weaknesses.

Here's a nice moveset you might want to give it:

Jolly nature
Choice Scarf
Technician
EVs: 252 Atk/4 SpDef/252 Speed
U-turn, Iron Head/Bullet Punch, Superpower, Aerial Ace/Pursuit

Great for pulling off the Choice Scarf.

So, going with my suggestion as well as PDude's, you should have this:

That should effectively give you two Physical attackers, two Special attackers and two set-up users.

 

[tinyranitar]

Man this team theme is Baton Passing so I gonna keep Heatran the way it is. Well considering changing item on latios too. Cloyster can take good care of blissey and chansey thanks to icicle spear. And volbeat to pass the invaluable tail glow +3 SAtk. Thanks for the advice on espeon (I don't know what to give him at first) :))

 

[Musica]

Volbeat is very terrible, don't use it cos it's very frail.

For a nice Pokemon to replace it, I recommend Scizor instead cos it has very little weaknesses.

Here's a nice moveset you might want to give it:

Jolly nature
Choice Scarf
Technician
EVs: 252 Atk/4 SpDef/252 Speed
U-turn, Iron Head/Bullet Punch, Superpower, Aerial Ace/Pursuit

Great for pulling off the Choice Scarf.

So, going with my suggestion as well as PDude's, you should have this:

That should effectively give you two Physical attackers, two Special attackers and two set-up users.

Scizor won't need speed, imo. It's slow as it is. Bullet Punch won't go well with Scarf. CB is much better. Or SD Scizor. Mienshao, Latios, Heatran and Cloyster should be the fast ones, while Scizor should maintain bulk to kill.