Since you're not going to be sweeping with this, you should probably use Fire Blast over Fiery Dance for greater power.
Volcarona (M) @ Leftovers
Trait: Flame Body
EVs: 252 HP / 20 Def / 56 SAtk / 180 Spd
Modest Nature (+SAtk, -Atk)
- U-turn
- Will-O-Wisp
- Fiery Dance
- Bug Buzz
This Volcarona set is beautiful. It usually starts the games because at turn 1 the stealth rock can't be present and it can do some damages without worrying about the residual damage from stealth rock. Will-o-Wisp can burn Terrakion, Gyarados, Landorus and similiar stuff, U-turn to scout and Bug Buzz and Fiery Dance are a strong STAB. 252 evs in HP and 20 evs in defense are useful for switch-in more easily against Genesect or another U-Turn users (Scizor for example) and to take advantage of Flame Body. I suggest you to try this set, it isn't bad at all.
You didn't explain the Speed evs, which seems to be a huge waste. I would probably put them in SpD to better check Genesect. Also i would remove Bug Buzz for Roost, as no bug type pokemon is going to stay in Volcarona anyway, and Roost obviously is a good move to have...
Volcarona (M) @ Leftovers
Trait: Flame Body
EVs: 252 HP / 20 Def / 56 SAtk / 180 Spd
Modest Nature (+SAtk, -Atk)
- U-turn
- Will-O-Wisp
- Fiery Dance
- Bug Buzz
This Volcarona set is beautiful. It usually starts the games because at turn 1 the stealth rock can't be present and it can do some damages without worrying about the residual damage from stealth rock. Will-o-Wisp can burn Terrakion, Gyarados, Landorus and similiar stuff, U-turn to scout and Bug Buzz and Fiery Dance are a strong STAB. 252 evs in HP and 20 evs in defense are useful for switch-in more easily against Genesect or another U-Turn users (Scizor for example) and to take advantage of Flame Body. I suggest you to try this set, it isn't bad at all.
So, this is one of my new babies. Obviously the point of the Shuca Berry is to ruin the GeneDug combo. But wait, isn't Shuca inferior to Shed Shell? Not so. Unlike SS, Shuca lets you use Heatran as a lure for Dugtrio. It can't OHKO you, letting you set up SR (especially against Lavos Sun), or else try and kill it through Sash with Magma Storm. Magma Storm is pretty underrated imo even on a non-trapping set; it prevents double switching, which is huge against stronger players, and is also substantially more powerful than Fire Blast once the residual damage is taken into account. I've been using this alongside Tyranitar, for fairly obvious reasons; with Dugtrio gone, Tyranitar has a field day against common weather teams. EV's are still geared towards special bulk, but the extra physical defense guarantees you'll survive a +1 DNite Outrage from full health.
Heatran @ Shuca Berry, Calm nature
252 HP / 68 Def / 190 SpDef
-Stealth Rock
-Magma Storm
-Earth Power
-(Will-o-wisp / Roar etc)
Yes Roost is better, it hasn't roost because it comes from a BW1 teamYou didn't explain the Speed evs, which seems to be a huge waste. I would probably put them in SpD to better check Genesect. Also i would remove Bug Buzz for Roost, as no bug type pokemon is going to stay in Volcarona anyway, and Roost obviously is a good move to have...
No good recovery, weak to hazards, weak to fighting moves. It's likely a good set, but OU might be a bit too much for it.
Walrein @ Leftovers
Ability: Ice Body
Nature: Careful
252 HP/ 176 Def/ 76 S.Def
Aqua Ring
Protect
Roar
Super Fang
Hails Bulk. Meant to be a phaser, Super Fang on a Defensive wall is extremely good and you can set up revenge kills on ALOT of pokemon (not counting ghost) with this guy before he goes down.
Tentacruel doesn't need to use Aqua Ring, isn't weak to Fighting, isn't weak to SR, works in Rain instead of Hail and...Aqua ring on top of Ice body and left overs isn't good recovery with Protect?
Why do we use tentacruel again outside of being a rapid spinner?
This set is fairly effective. I had tested it out a few weeks ago and it put in a lot of work. It can somewhat function as a Genesect-esque scout lead as well. I would put Volt Switch over U-turn, however, because being able to get out against Thundurus-T and Ground types is a lesser advantage than being able to hit and run with a decently powerful Volt Switch.
Zapdos @ Choice Scarf
Trait: Pressure
EVs: 252 SAtk / 252 Spd / 4 Def
Timid Nature
- Thunderbolt
- Heat Wave
- Hidden Power [Ice]
- U-turn / Volt Switch
Zapdos is an under-appreciated Poke in OU, but it has great surprise factor with a Choice Scarf set. Base 100 allows it revenge a great amount of targets. Comparatively, it losses to Thundurus-T due to its inability to always outspeed base 100's. However Zapdos' advantage is surprise factor, better bulk, and Heat Wave. These all allow it to surprise Genesect leads he mistake it for a bulky set and then proceed to get OHKO'ed. It's better bulk comes in handy for teams that struggle to check Tornadus-T. Like Thundurus-T it an keep momentum with U-turn or Volt Switch. Can't wait for Lightning Rod though since Volt Absorb makes Thundy better. +1 Sp. Atk will allow for some cool late game sweeps compared to getting health with Volt Absorb.
If a poke does enough damage to you, so that you are succesfully revenge killed by pretty much anything, then this doesn't count as a poke you can set-up on. Almost all of the pokes you mentioned do more than 30% to Swoobat even after a CM, meaning that every single faster or priority poke will be able to revenge kill you, as you will get one kill at best.It can set up on certain Fighting-types (Breloom without Stone Edge or Thunderpunch in particular, assuming Sleep Clause), Deoxys-D, Tentacruel, Forretress without Gyro Ball (HP Ice version is better), Espeon, Xatu, Specs Keldeo (Hydro Pump outside of Rain does 84.53 - 99.64% to +2 Swoobat, and Swoobat always OHKOs back with +2 Giga Drain), Special Landorus before the Rock Polish, any Pokemon locked into a Ground or Fighting move (Jolly CB Terrakion doesn't get any more than 50% with Close Combat), Leftovers Gengar, Celebi without TWave or the appropriate Hidden Power, Gastrodon, and a few other things that I'm forgetting. It's fast enough to handily outspeed a large portion of OU and threaten a revenge kill to something it outspeeds, and when that something can't do anything in return to Swoobat it's pretty much a free +2. Admittedly it has big problems with priority (besides Mach Punch, of course), but with proper support it makes an amazing late-game cleaner. I never thought about Screens support to be honest (I never think about that, Screens waste turns that I could be using to kill stuff imo), but that sounds even better.
Also, it's a freaking heart bat.
EDIT: LO Tornadus-T does 65.82 - 77.69% to +2 Swoobat.
Mamoswine @ Salac Berry
Trait: Thick Fat
EVs: 252 Atk / 4 SDef / 252 Spd
Adamant Nature
- Earthquake
- Ice Shard/Stone Edge
- Icicle Crash
- Substitute
I've been messing around with this set on an HO team and it's pretty good. The idea came from the fact that so many teams relied on revenging mamoswine. It revenges dragons early game, and sweeps late game once rotom-w and counters are weakened/removed.
252 +2 Atk Life Orb Garchomp Dragon Claw vs 252 HP/184 Def Gliscor (+Def) : 62,71% - 73,73%
Garchomp @ Leftovers / Life Orb
Trait: Rough Skin
EVs: 252 Atk / 4 SDef / 252 Spd
Jolly Nature
- Hone Claws
- Dragon Rush / Dual Chop
- Earthquake
- Fire Fang / Stone Edge
Garchomp, I noticed, has access to a variety of moves with high power, but low accuracy and access to Hone Claws, so why not make a boosting set with those moves? Dragon Rush and EQ for stab and Fire Fang / Stone Edge for coverage. Plus, you get the added benefit of being able to switch out instead of being locked into Outrage. Maybe outclassed in terms of raw power by the SD set but still a good set nevertheless.