Is my OU team good? Any changes to make it better?

Heatran (M) @ Leftovers Trait: Flame Body
EVs: 80 HP / 216 SAtk / 8 SDef / 204 Spd
Timid Nature (+Spd, -Atk)
- Lava Plume
- Earth Power
- Substitute
- Toxic


Heatran is my favorite tank. He is bulky, has great typing and is strong. Put him in when the chance arises, Sub and then Toxic or sweep.



Jellicent (M) @ Leftovers
Trait: Water Absorb
EVs: 248 HP / 172 Def / 36 SDef / 52 Spd
Bold Nature (+Def, -Atk)
- Recover
- Scald
- Will-O-Wisp
- Taunt


Jelli is great. Taunts the hell out of everyone, WoW on physical attackers. Scald as well. Recover to heal. He is a great Sp. Wall and Taunter.



Chavenin (Amoonguss) (F) @ Leftovers
Trait: Regenerator
EVs: 188 HP / 140 Def / 180 SDef
Calm Nature (+SDef, -Atk)
- Spore
- Giga Drain
- Hidden Power [Ice]
- Clear Smog


Amoonguss. I fell in love with this mushroom long ago. It's bulky, has Spore and Regenerator. It's my favorite phazer with Clear Smog and it's plain great. Can take on Breloom and Keldeo too.



Neuron (Reuniclus) (F) @ Leftovers
Trait: Magic Guard
EVs: 220 HP / 252 Def / 4 SAtk / 32 SDef
Bold Nature (+Def, -Atk)
- Focus Blast
- Calm Mind
- Psychic
- Recover


Once it sets up, its a pain. It's bulky, it CMs up and then it sweeps. It's a great bulky Special Sweeper.



Health (Blissey) (F) @ Leftovers
Trait: Natural Cure
EVs: 212 HP / 252 Def / 44 SDef
Bold Nature (+Def, -Atk)
- Wish
- Protect
- Seismic Toss
- Thunder Wave


Blissey cares for her teammates. She keeps them alive with Wish and she is a great Sp. Wall and she can cripple attackers with Twave.



Acrobat (Gliscor) (F) @ Flying Gem
Trait: Poison Heal
EVs: 244 HP / 44 Atk / 116 Def / 104 SDef
Impish Nature (+Def, -SAtk)
- Earthquake
- Swords Dance
- Acrobatics
- Substitute


He is good. Can take on Terrakion, Breloom and Conkeldurr and it can hit back with SE damage. It can set a sub and then SD and sweep. It's my physical sweeper.



What should I change? It's pretty good but I still lose to some tough people. What's my team weak against?

I'd like to know how you come up with your EV spreads.

I'd make Heatran have 252 SAtk/4 SDef/252 Spe just so it can outspeed slower walls and Toxic/set up a Substitute on them before they land a status on their own on it. Fire Blast is ideal over Lava Plume for more power; the latter move is only good on defensive sets. Flash Fire is still Heatran's preferred ability so that its Fire neutrality becomes an immunity.

44 Speed EVs is just enough to let Jellicent outspeed minimum Speed Skarmory. Since this is a physically defensive set you're using, the EV spread should be 248 HP/216 Def/44 Spe to outspeed said Pokemon and have as much physical bulk as possible (since its Special Defense is high enough already).

Amoonguss' EV spread should be 252 HP/28 SAtk/228 SDef to always break Keldeo's Substitutes with Giga Drain and having as much special bulk as possible.

IMO, it's worth it for Reuniclus to have max HP/max Defense, again for ideal physical bulk.

Since Blissey's HP is already very high, its spread should be 4 HP/252 Def/252 SDef with a Calm nature. The spread you're currently using makes it more prone to special moves than it should be.

I'd rather have Gliscor have max Attack/max Speed with an Adamant nature for more power behind its Acrobatics, as well as a LOT more Speed to outspeed stuff. Hyper Cutter should be the ability to use to not let Intimidate screw you over. If you still want to use Poison Heal, Gliscor is better off with defensive sets:
-Substitute
-Toxic
-Earthquake
-Protect/Taunt/Roost
Nature: Impish
EVs: 244 HP/28 Def/236 Spe
Item: Toxic Orb
Ability: Poison Heal

or
-Earthquake
-Taunt/Toxic
-Ice Fang/Toxic/Stealth Rock
-Roost/Protect
Nature: Impish
EVs: 244 HP/248 Def/16 Spe
Item: Toxic Orb
Ability: Poison Heal