I think I tested out a version of this team yesterday, and I liked it. This team may have been "improved" but you still have some major problems. Sorry if I change to much of your team here xD
So first of all massive weaknesses stand out. CBand Terrakion wrecks most teams. This team however has no reliable check to it. Nothing on the team can safely switch on in it, leading to you having to fodder off a Pokemon each time it switches in, just so you can get a free switch into Tornadus. This is a result of a generally slow team which tries to focus on beating the core metagame rather than the individuals.
Other certain sweepers such as Scizor also give you a hard time with its powerful U-turns destroying half of your team. This is partly as a result of you using Blastoise over Tentacruel. Tentacruel may not be so bulky on the physical side, but it does have some very nice resistances. It has effectively everything Blastoise has apart from an unfortunate ground weakness which isn't much of a problem for your team.
Another thing you could do is loose Tenta and replace it with Jellicent who will completely shut down sweepers such as Terrakion and Scizor. It also check Pokemon such as Poli pretty well. This is the change I would make, though you would loose your rapid spinner.
The changes I have made
OK so I have tested the new teams a few times. It doesn't appreciate hazards, if you are stupid enough to let the opponent set all 4 layers of rocks and spikes up like me. It has better synergy than the current team as well as deals with more threats.
Here is a replay of me somehow not 6-0 ling the worst battler ever. Apparently Shiftry gets sucker punch. Who knew? Funny replay :3 such a bad battler. Anyway.
Politoed @ Leftovers
Trait: Drizzle
EVs: 252 HP / 248 Def / 8 Spd
Bold Nature
- Protect
- Toxic
- Scald
- Encore
Landorus (M) @ Life Orb
Trait: Sheer Force
EVs: 252 SAtk / 252 Spd
Timid Nature
- Earth Power
- Focus Blast
- Rock Polish
- Hidden Power [Ice]
Tornadus (M) @ Choice Scarf
Trait: Prankster
EVs: 252 SAtk / 252 Spd / 4 Def
Timid Nature
- U-turn
- Hurricane
- Hidden Power [Ice]
- Focus Blast
Terrakion @ Choice Band
Trait: Justified
EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature
- Close Combat
- Stone Edge
- Hidden Power [Ice]
- X-Scissor
Jellicent @ Leftovers
Trait: Water Absorb
EVs: 52 Spd / 252 HP / 204 Def
Bold Nature
- Scald
- Will-O-Wisp
- Taunt
- Recover
Ferrothorn @ Leftovers
Trait: Iron Barbs
EVs: 4 Atk / 252 HP / 252 SDef
Sassy Nature
IVs: 0 Spd
- Leech Seed
- Stealth Rock
- Gyro Ball
- Power Whip
So this is the altered team. I have used it 5 times so far and lost once. Mainly because Focus Miss missed twice in a row before my opponent got a crit on Jellicent which really sucked.
Politoed
Politoed has gone defensive. That works until we come across Skarm who sets up easily on it. Your current set is also fine to use, but I would run Toxic or HP grass over perish song.
Toxicroak
Toxicroak has been replaced as it doesn't do much. It isn't doing much for your team apart from providing fighting support. Terrakion hits everything hard. Usually something will die when it will switch in. It deals nicely with Thundarus-T and hits Landorus-T surprisingly hard.
Blastoise
Blastoise has been replaced with Jellicent. It shuts down sweepers and makes good synergy for the team. If you feel spinning is a big issue though then Tentacruel is the better option. However Tenta leaves you open to Mamo. You could also use Starmie as an offensive spinner and rely on free switch ins to deal with Terra.
Kyurem
Replaced with Lando. Not as much pressure to spin + its naturally faster and wrecks havoc. Whereas Kyurem hits hard and is walled by half the meta.
Tornadus
Love it. I have changed nothing but the nature which will ensure it outspeeds other scarf users such as Salamence.
Ferro
The standard set evs ensures it takes certain physical hits better while not being 2hko'd by +1 Hax earthquake. I don't think that's really a problem. The sets outdated and full SDef is the way to go in a rain infested meta. You will appreciate being able to sponge Focus Miss.
Thats what I have changed to your team briefly. Any quires then just ask away. It is a nice and fun team to use. Sorry for changing 3 members :L Almost had to be done
