Politoed - It looks good, but consider Encore > Perish Song. You'll be able to lock opposing pokemon into support/set-up moves, giving you either a free switch and the ability to take them out, or forcing them to switch.
Volcarona - Once more, this looks good but go with Fiery Dance > Fire Blast, as it can raise your SAtk, which just makes you all the more deadly, or if you don't care for a Fire STAB, consider Roost to ease SR damage.
Dragonite - I prefer running Dragon Claw > Outrage on non-choiced sets, because it allows you to switch moves. One thing that comes to my attention is that you are walled by Ferrothorn, so consider Brick Break over Earthquake.
Ferrothorn - I fail to see why you are running 0 Spd IVs without Gyro Ball. Run Stealth Rock over protect, as it will support your sweepers by loads. Also, Gyro Ball is an option if you replace Thunder Wave for Spikes/Protect.
Toxicroak - Black Sludge is nice, but you're getting healed by the rain, so why not try a Life Orb for more power to abuse? Dry Skin will ease the LO recoil considerably, and I recommend Drain Punch over Cross Chop, as it can heal you and is all around more reliable.
Breloom - I like Breloom, but he doesn't synergize with this team and you need a spinner. For a spinner I recommend Starmie.
Starmie @ Life Orb/Leftovers
Trait: Natural Cure
EVs: 4 HP / 252 SAtk / 252 Spd
- Hydro Pump
- Ice Beam
- Rapid Spin
Rapid Spin eases your rock weakness, and really supports Dragonite and Volcarona. Hydro Pump is STAB and hits hard with a rain boost. Thundebrotl and Ice Beam provide great coverage, and onc Starmie's spinning duties are over it serves as a great revenge killer and late-game sweeper.
Sorry it was kind of short, but I didn't see a whole lot that needed done. Overall it's a nice team ;)