Hey again! Got the request.
Since you want to keep both ScarfGar and Hydreigon, I'll work around them. So first of all, I see two massive threats in
DD Dragonite and Volcarona. The former can set up on Infernape and Ferrothorn (and Jirachi to an extent) while the latter can set up on Gengar, Ferrothorn, Starmie (assuming Sun) and Hydreigon. Volcarona also uses Gengar as set-up fodder, so locking yourself into Destiny Bond with Gengar to take it out would cause you to lose the game entirely. I think Infernape fits quite nicely on this team as it supplies a fighting type and a fire-water-grass core. My only beef with him is the set. Without Vacuum Wave, it's easily revenge killed and already difficult to set up. I feel like you'd do much better with the
MixApe set, which also deals with your Volcarona problem. Infernape resists both its STABs and Giga Drain, so it's a good thing to switch into when it's trying to boost. Here's the set that I think would most benefit your team:
Infernape
(F) @ Life Orb
Trait: Blaze
EVs: 252 Atk / 4 SAtk / 252 Spd
Hasty Nature (+Spd, -Def)
- Stone Edge
- Overheat
- Close Combat
- Hidden Power [Ice]
*IVs should be 30 HP, 30 Def
I changed the nature over to Hasty so that Volcarona's STABs won't OHKO you. Basically, the set here is more characteristic of Infernape's job in OU. Hit hard and run away. Stone Edge OHKOs Volcarona before it can hope to sweep you while Overheat and Close Combat function as absurdly powerful STABs. HP Ice deters Landorus(-T), Dragonite, and others from setting up on you. After all, prevention is the best protection.
Moving on with the same ideal of prevention, I feel like a change in Ferrothorn's moveset is in order. To make sure that Dragonite cannot find a single opportunity to set up,
give Ferrothorn Gyro Ball over Stealth Rock. I know someone already suggested this, but I really want to enforce it. Making sure Dragonite cannot set up is the best way to deal with it. It also helps against other Dragons and especially Rock Polish Landorus, which can also give you massive amounts of trouble. Since you're now missing Stealth Rock,
remove Sunny Day from Jirachi in favor for it. You already have a spinblocker, so having 2 hazards is definitely supported. And let's face it, your team already hates Sun anyway. I feel like you're able to deal with the other weathers just fine, so it's worth it.
And lastly, I do want to change something on Gengar. You are really weak to DD Dragonite and Rock Polish Landorus, as stated before, so I think it would be a really good idea to
replace Thunderbolt with Hidden Power [Ice]. One of the greatest things about Gengar is its immunity to ExtremeSpeed, and since it outspeeds even +2 Dragonite, you'll always be able to revenge kill it without any problems. Similarly, Rock Polish Landorus almost never has Psychic, and since its HP Ice never kills Gengar, you'll have a nice answer to that as well. I don't think you have a problem with Skarmory, Gyarados, or bulky waters, so I doubt you'll miss Thunderbolt.
Lastly, I just want to throw it out there that only Life Orb
Hydro Pumps on Starmie OHKO 4HP Gengar. Against Deo-Gar HO teams, this can be the difference between winning and losing because you'd be forced to switch out of Gengar (or die to a Shadow Ball after it lives a Surf) if it comes in to spinblock. I know you like Surf's accuracy, so if you want a solid method of killing Gengar, I'd recommend
Psyshock over Thunderbolt. It has pretty decent neutral coverage and always OHKOs Terrakion in Sand, Keldeo, Breloom, Conkeldurr after Spikes, and others. I don't really see the need for Thunderbolt on your team since Ferrothorn loves going face-to-face with bulky waters to set up Spikes and get some more HP with Leech Seed.
That's all! Cool team dood~ Good luck!