Personally, I use this set:
Item: Leftovers
Nature: Adamant
EV: 252 HP/123 Atk/123 Spe
Moveset:
- Brave Bird
- Flare Blitz
- Roost
- U-Turn/Steel Wing/Will-O-Wisp
Brave Bird and Flare Blitz are its STABs, but with two recoil moves, its lifespan may get short. That's where the 252 HP EVs come in handy. Roost is used to heal recoil damage (pairing it will Leftovers will let it recover more HP) and lose a double weakness to Rock and a weakness to Electric, in exchange for a weakness to Ground. On the last moveslot, U-Turn is my preferred option since it lets it scout opponents and switch into a proper counter (Ex.: U-Turn on Rhyperior, then switch onto Chesnaught). Steel Wing may also be used over U-Turn to at least deal great damage to threats like Gigalith and Rhyperior, being more useful if their switch is predicted. Will-O-Wisp is the third and decent option, crippling other threats like Barbaracle.
Counters: Barbaracle, and Relicanth are its best counters. They resist all of its moves and can set-up in its face or OHKO with Stone Edge or Head Smash, respectively. However, they must look out for the rare Will-O-Wisp, as even though they defeat Talonflame, they will be crippled for the rest of the match. Tyranitar, Rhyperior and Gigalith are respectable counters too, since they also resist its STABs and are more powerful than the aforementioned, however, Steel Wing may cause substantial damage to them and Will-O-Wisp cripples them, too. Hippowdon resists its attacks, can shrug off damage with Slack Off, its sandstorm negates Leftovers recover and it can proceed to set-up Stealth Rock or OHKO Talonflame with Stone Edge. However, it still gets crippled by Will-O-Wisp.
Rotom-W and Rotom-H are pretty good counters as Rotom-W doesn't really mind a burn and Rotom-H is immune to Will-O-Wisp, and they can OHKO with Volt Switch, or Hydro Pump in Rotom-W's case. Heatran can come into Flare Blitz and increase its Fire STABs with its ability, Flash Fire, in addition to Taunt it so it cannot recover, set-up Stealth Rock or cripple it with Toxic.
Any check? Feel free to reply.