The team as a whole, like I said, is GREAT in terms of resistance coverages, BUT... I worry that you don't have enough Pokemon that can just do big damage outright. You might end up against a bulky wall that you can't kill because you just can't deal enough damage fast enough- Granbull's the only one on the team that can deal with something like that, MAYBE. Torkoal seems like something that might die off early, while Gastrodon and Sableye need to stall to do any real damage. Exeggutor needs Sunny Day to work AT ALL, Swalot needs to Curse up... See the pattern here? As much as I hate to say it, today's metagame is VERY speed oriented- if you take too long to setup, you'll probably just get swept.
Onto the individual members of the team...
Torkoal's Atk is NOT that bad- especially considering that Explosion considers the target to have HALF their usual Def? That's pretty
awesome- Torkoal laughs at Chansey switch-ins. I'd give it 220 HP EVs, though, for max Leftovers recovery without being wasteful on EVs. That gives you 32 more EVs to spread about your Sp.Atk or something.
Since Steel types wall this Gastrodon for the most part, I think I'd sooner give it Earthquake or Earth Power over Surf. That seems to be a common weakness around your whole team- Steel types have a pretty easy time with it. 212 HP EVs for max Lefties recovery- 40 spare EVs to play with.
Since you already have a Toxistaller, I'd definitely run WilloWisp over Toxic on Sableye. Not only does it start dealing damage faster than Toxic, but it extends Sableye's survivability. Shadow Sneak seems pretty pointless, considering Sableye's got no Atk investment. I'd sooner replace it with Recover, Confuse Ray, or maybe Knock Off. Even Taunt is an option, being that you can use it to keep things from using Recover, or you can Snatch to swipe Recovers, Wishes, etc. Play around, see what suits your fancy.
Exeggutor has a lot more going for it than people believe. You instantly thing SUNNYBEAMER, immediately dismissing his ability to do much anything else. SunnyBeamer is not only predictable, but Sunny Day doesn't really do ANYTHING for the rest of the team. Besides being pretty bulky, Exeggutor makes a great Physical Sweeper. He maxes at 317 Atk, afterall, gets Stun Spore and Sleep Powder, and has the bulk to put up a Swords Dance or a Curse or two before going wild with Zen Headbutt and Wood Hammer. Besides that, it also gets both Screens, Trick Room, Leech Seed, and Explosion. Have fun with it. This is probably the one Pokemon I'd consider replacing, since a physical set is easily walled by Steel types, and Exeggutor's SunnyBeaming abilities are cut short by the fact that it doesn't benefit the rest of the team. Cradily, Sceptile, Meganium, and Torterra are good replacement options- Cradily gets Earth Power for Fire and Steel types, while Sceptile, Meganium, and Torterra get Earthquake. Torterra runs a good Polish set, while Sceptile's naturally speedy and mixes well. Meganium is faster than people think, and also has the advantage of dualscreens, and Aromatherapy support.
Your Swalot's another one of those Pokemon that are EASILY walled by any given Steel type. As such, I'd highly recommend Earthquake over Gunk Shot- it's generally much more reliable. I'd keep Pain Split, and experiment between Curse and Stockpile, with varying EV spreads, because either could work. Sticky Hold's better than Liquid Ooze, really- if you switch in on a predicted Trick or Switcheroo, you essentially get a free turn to Curse up while they're forced to switch. Try something like this:
Swalot @Black Sludge
-Ice Punch
-Earthquake
-Curse
-Pain Split
Sticky Hold, Sassy
236 HP, 72 Atk, 200 Sp.Def
Granbull seems fine to me- good for absorbing status, but Headbutt REALLY has to go for Return or Facade- consider that Headbutt and Facade have the SAME POWER normally, and that Facade gets DOUBLE power with a status effect, which Granbull is meant to suck up with Quick Feet. Crunch with Close Combat makes for NEAR perfect coverage, note. Facade is for when you've absorbed a Toxic or T-Wave, and Ice Punch/Fire Punch is for coverage- you'll probably want Ice Punch.
Granbull @Choice Scarf
-Facade
-Close Combat
-Crunch
-Ice Punch/Fire Punch
Quick Feet, Adamant
252 Atk, 252 Spd, 4 HP