Rate my Pokemon Showdown OU Team

Question

I developed this team a while back, and I'd like to get some feedback on it.

Breloom @ Leftovers
HP: 252 / Atk: 252 / SpD: 4
Ability: Technician
Nature: Adamant
-Spore
-Mach Punch
-Bullet Seed
-Drain Punch

Breloom is a beast. Spore (Duh). Mach Punch, priority plus Technician boost. Drain Punch to eat away at the foe's HP while they're asleep. Bullet Seed does a ton with Technician boost.
***

Slowbro @ Rocky Helmet
HP: 252 / Def: 252 / SpA: 4
Ability: Regenerator
Nature: Bold
-Slack Off
-Shadow Ball
-Psychic
-Scald

Slowbro is a great tank with great moves. With regenerator and slack off he gains HP back quickly. Rocky Helmet takes off some HP on physical sweepers when you switch in. Attacks for coverage.
***

Zapdos @ Leftovers
HP:4 / Spe: 252 / SpA: 252
Ability: Pressure
Nature: Timid
-Air Cutter
-Signal Beam
-Thunderbolt
-Heatwave

Not much to say here, Zapdos is cool looking, with great speed and attacks.
***

Medicham-Mega @ Medichamite
Atk: 252 / Spe: 252 / SpD: 4
Ability: Pure Power
Nature: Jolly
-Fake Out
-Drain Punch
-Bullet Punch
-Ice Punch

Mega-Cham is one of my favorite megas, it hits hard and fast. With Huge Power, Fake Out does a ton, Drain Punch to gain back HP, Bullet Punch for Fairies and priority, and Ice Punch to deal with Flying/Dragons.
***

Heatran @ Air Balloon
SpA: 252 / HP: 252 / SpD: 4
Ability: Flash Fire
Nature: Modest
-Stealth Rock
-Flamethrower
-Earth Power
-Flash Cannon

Air Balloon + Flash Fire allows Tran to switch in on fire and ground-type moves. Stealth Rock is one of the best entry hazards, and the other moves for STAB + coverage.
***

Cloyster @ King's Rock
HP: 252 / Atk: 252 / Def: 4
Ability: Skill Link
Nature: Adamant
-Icicle Spear
-Rock Blast
-Rapid Spin
-Razor Shell

I feel like Cloyster under rated. Even though he's in the UU tier, he does wonderfully in OU. I'm not a fan of the Shell Smash set, but I love the Skill Link + Icicle Spear + Rock Blast + King's Rock combo. Skill Link for the 5x hit moves, and Kings rock for flinching. Razor Shell for water STAB and Rapid Spin to clear hazards.

Comments

Balloon Heatran? I don't like it, the balloon pops after a random attack. It can give a one time immunity to quake, but lefties recovery is much more precious. I like your Cloyster, but you should definitively try Shell Smash. You're not a fan of that move, but try it at least if you didn't. Mega-Cham is not very fast, I find it average at best but if you like it, it's your choice. Good moveset.
Zapdos sucks tho. I might rate that team in depth if I find more problems.

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Lava Plume < Flamethrower
Breloom @ Focus Sash
Nature: Jolly
Ability: TEchnician
EVs: 252 Atk/ 252 Spd/ 4 HP
MOVES
-Spore
-Bullet Seed
-Rock Tomb
-Mach Punch

Cloyster is 50/50

Zapdos, keep everything cept air cutter and signal beam. Roost/ T-WAve

SloBro gotta have calm mind

Answer 1

Here are some changes that you could make to your team:
1. For Slowbro, swap shadow ball with thunder wave so that you can paralyse any sweepers who try to set up on you.
2. Swap drain punch for rock tomb(gets the technician boost) to take care of your x4 weakness to flying. Also, you have leftovers for recovery already.
3. Mega-medicham doesn't need drain punch because it learns recover. Also, ice punch is not needed as you have a Cloyster so replace it with fire punch to take out most hazards setters(Pokemon that set up hazards). Use fake out to break any Pokemon with sturdy then fire punch to finish them off.
4. For Zapdos, replace heat wave with roost for more recovery as you should have fire punch on Medicham and Heatran.