Torkoal is one of the pokémon that greatly benefited from the generation shift in the form of a new ability in Drought. Now joining the club of weather setters, in addition to its great defensive stats and support moves, Torkoal is a significant asset to its team.
Turtlin' Along
Torkoal
Ability: Drought
Item: Leftovers/Sitrus Berry/Iappa Berry
-Rapid Spin
-Yawn/Clear Smog
-Flamethrower
-Solar Beam/Toxic/Yawn/Clear Smog
Nature: Bold [+DEF, -ATK]
EVs: 248 HP/252 DEF/8 SDEF
This Torkoal embraces its defensive roots, while providing support to the team. Rapid Spin is there to remove any entry hazards the opponent may have setup (Torkoal is admittedly a poor Rapid Spinner, but it works, and this set will be switching a lot). Yawn and Clear Smog are used to prevent Torkoal from being setup bait. Yawn forces a nasty Catch 22 -Swap out and lose momentum, or stay in and fall asleep. Clear Smog is for those who think they can setup in front of Torkoal (and works better against boosting RestTalk sets than Yawn). Flamethrower is to prevent becoming Taunt Bait (being preferred over Lava Plume and to avoid having the Burn Chance screwing you over). Solarbeam is to ruin any Water/Ground/Rock types day (lest they are named Politoed, Pelipper, Hippowodon, Aurorus or Gigalith). Toxic maybe more preferable than Yawn against bulkier opponents (or those immune to sleep) or if there is a Sleep Clause in effect. Item is for recovery, EVs are to maximize bulk.
The main problem with this set is that Torkoal is still rather passive, and can only take out weakened opponents that are weak to its moves, or with Toxic. Yawn and Clear Smog help a lot, but it still hurts
Other Options
-Heat Rock: More sun for everybody!
-Rest: Torkoal's only reliable recovery outside of items. Sleep Talk and Chesto Berry will also be mentioned for synergy.
-Explosion: Exploding turtles are fun!
-Stealth Rock -thanks to Gen IV, this was once given to everybody. Works great on a defensive Torkoal set. (TRANSFER ONLY)
Tipping Torkoal
So how to break Torkoal? Not that difficult. Outside of Trick Room, Torkoal is horribly slow (because its a Turtle) and 70/70 Special bulk is a rather large target for any special attacker in the tier. Goodra, Heliolisk (especially Solar Power Heliolisk), Jolteon, Hoopa, Sharpedo, etc. All reliably 2HKO Torkoal. While Torkoal can run Physical sets (its ATK being equally bad as its SATK), it doesn't change the fact that it has no good physical STAB move to take advantage of it. Thus Bulky sponges like Florges, Goodra, Mantine, Milotic can easily run out Drought's clock while weathering Torkoal's sun boosted assaults, though all of them hate Toxic, and Yawn can force them out. Despite being an entry hazard remover, Torkoal hates entry hazards, being hit by all of them and taking extra damage from Stealth Rock. Couple this with no reliable recovery outside of Rest, and Torkoal is rather easy to beat down with passive damage and attacks. While 140 DEF is phenomenal, that 70 HP lets down Torkoal time and time again. Powerful physical sweepers like Rhyperior, Aerodactyl, Gigalith and Donphan can all reliably 2HKO Torkoal with their STAB moves, though an unlucky burn would make Torkoal nigh impossible to break physically.
The other problem is preventing Torkoal from supporting its team, which considering its job is essentially done the second it hits the field makes this trickier. Opposing weather setters, like Politoed, Pelipper, Hippowodon, Aurorus, Tyranitar or Gigalith all ruin Torkoal's sun, and can beat it one on one. However, they must come in after Torkoal, because due to its low speed, Torkoal outslows every other weather setter in the game and thus Drought will overwrite their weather if they switch in simultaneously. Golduck and Altaria with Cloud Nine also deserve a mention, especially the latter having a support movepool that counters Torkoal's fairly effectively and can beat it one on one.