Breloom@ Toxic Orb
Ability: Poison Heal
EVs: 252 Atk, 252 Speed, 4 HP
Nature: Jolly
Substitute
Seed Bomb
Spore
Leech Seed
OR
Subtitute
Focus Punch
Spore
Seed Bomb
The first set is the annoying Breloom set. It basically aims to sap as much health as possible and stall. Seed Bomb > Drain Punch because nothing is immune to Seed Bomb (except Sap Sippers).
The second set is a SubPunch set. Since you need time for Focus Punch, Spore and Substitute will provide you with that.
Gengar @ Black Sludge
Ability: Levitate
EVs: 252 Sp. Atk, 252 Speed, 4 HP
Nature: Timid
Shadow Ball
Thunderbolt
Focus Blast
Protect/ Substitute
I wouldn't Choice Gengar; it's fast enough and has a high enough special attack/ speed. If you wanted to give it a boost, let it hold Life Orb instead.
Gallade @ Leftovers
Ability: Justified
EVs: 252 Atk, 200 HP, 56 Speed
Nature: Jolly
* Bulk Up
* Close Combat/ Drain Punch
* Shadow Sneak/ Night Slash
* Psycho Cut
Steadfast doesn't come into much use. I know that Fake Out is common enough, but it's not as if you opponent will be using that on you again after they see that you have Steadfast.
To deal with Ghost types, Shadow Sneak for priority or Night Slash for more damage. You can always go Rock Slide over Psycho Cut as well (I'm only suggesting Rock Slide due to Stone Edge's low accuracy and you have Bulk Up anyway).
However, I would ultimately suggest you replace either Breloom or Gallade (probably Gallade) with a Pokemon that is resistant to flying. Both Breloom and Gallade are pretty slow, so unlike fighting types such as Mienshao, they can't go before many flying types.
Suggestion for that is Rotom-W.
Rotom-W @ Leftovers
Ability: Levitate
EVs: 232 HP, 232 Sp. Def, 44 Sp. Atk
Nature: Calm
* Hydro Pump
* Volt Switch
* Will-O-Wisp
* Thunderbolt/ Pain Split
OR
Rotom-W @ Choice Scarf
Ability: Levitate
EVs: 252 Sp. Atk, 252 Speed, 4 HP
Nature: Modest
* Thunderbolt/ Volt Switch
* HP Ice
* Hydro Pump
* Trick
Rotom-W will cover Breloom's Fire weakness too. You can either make Rotom-W bulky in order to take a few hits, or give a Choice Trick set to mess up your opponent.