OK let's start!
Before we get too it you have a small water weakness even with Vaporeon helping out. if you want replace Forretress with Ferrothorn and bob's ya uncle. I will suggest a set later.
It's fine. if you want to replace taunt with trick and W.O.W with Torment. Have it hold any choice item then use Trick and follow with Torment. It fails to do any damage every other turn allowing you to recover,and attack soon after. But this is just preference,that set is fine.
As I said before, I suggest replacing Ferre with Ferro. This is Ferro standard set.
Ferrothorn @ Leftovers
Trait: Iron Barbs
EVs: 252 SDef / 252 HP / 4 Atk /
- Leech Seed
- Power Whip
- Stealth Rock
- Thunder Wave
Hope this works out better. Sorry I am being lazy with my typing today I will make the reasons why better later but the suggestions are fine.
The simple yet effective Heatran/Vaporeon/Ground type(Gliscor) core. It is in theory quite hard to beat. Landorus,however, can shut down most of it. Once Vaporeon is out then Hidden power ice and earth power = OHKO's for Jirachi, Gliscor and Heatran. Tornadus can do the same with Focus blast and Hidden power Ice. so..
Vaporeon is one heck of a staller. Surpassing it's cousin Umbreon by getting to OU. Although it can be used without rain, Rain + Hydration + Rest is where it really shines. You can keep it if you want but I prefer this...
Gastrodon @ Leftovers
Trait: Storm Drain
EVs: 252 Def / 252 HP / 4 SAtk
- Clear Smog
- Earth Power/Ice beam
Go Go Gastrodon! This is one set to give it. Clear smog upsets sweepers trying to set up. Scalds high burn rate again annoys the hell out of physical attackers as well as doing slow damage. Earth power is just...there,but Ice beam is preferred to KO grass. Recover is to help stall.
OK Heatran doesn't seem to bad but why give a all out attacker with little defence SR? We have Jirachi for that if we wanted it. If you want to keep it an all out attacker then use that but replace SR with perhaps... flash cannon for powerful stab or maybe Dragon pulse to take out monsters like Garchomp and Dragonite. If you want a defensive Heatran to set up then this will work...
Heatran @ Air Balloon
Trait: Flash Fire
EVs: 252 SDef / 252 HP / 4 SAtk
- Stealth Rock
- Lava Plume
So W.O.W cut's attack giving it longer life. Lava plume is the main attack. SR like you wanted and Roar to accompany it. As well to get rid of pokemon resisting fire.
I give Gliscor many tasks throughout my use of it. It can physically stall the hell out of things, go all out offensive, or lie somewhere in between. To put it simply, I don't like your set. Try this out...
Gliscor @ Toxic Orb
Trait: Poison Heal
EVs: 252 Atk / 184 HP / 72 Spd
- Stone Edge
- Swords Dance
by using Protect on the first turn or whenever you predict an attack, you gain back sizeble HP per turn. this is to heal of any damage you could of taken when setting up S-Dance. StoneQuake is pretty Epic coverage on this guy.
So, this also means you have to worry less about pokemon like Thundurus and Landorus. If they really scare you ScarfSwine( Mamoswine with choice scarf) or MamoBand (Mamoswine with choice band) both make great counters. Replace gliscor with it since they are both Ground types.
Rachi doesn't seem too bad a choice. But you got the set all wrong. I will show you physical Haxrachi!
Jirachi @ Leftovers/choice Scarf
Trait: Serene Grace
EVs: 252 HP / 32 Spd / 224 Atk
- Iron Head
- Body Slam
There! The art of Haxrachi! Only use trick if you have choice scarf and kept your set on Sableye.
I'm a but lazy today it seems. Just use theses until some better suggestion comes along OK? Hope I helped at all..