Personally I don't really like Talonflame, but it's really good in OU, I think that it is one of the best revenge killer in the metagame.
Maybe it's only flaw is the x4 weakness to the Stealth Rocks and the not so much high Atk, but when you have a priority of 120 BP that also gets STAB and access to SD, who cares.
It can also have different sets, so he can fit in many teams with a different role, he can be a revenge killer if he holds a Choice Band, he can be a sweeper thanks to the high speed, SD and +1 priority Brave Bird, he can even be a stallbreaker thanks to Taunt.
He can also ruin some of his checks: Landorus-T risks a Will-O-Wisp on the predicted switch in, Rotom has to be careful of Liechi Berry+Natural Gift, Heatran and Tyranitar of Salac Berry+Natural Gift, but I don't see these sets very often on the ladder, so Rotom-W, Tyranitar and Heatran still do a very fine job on checking Talonflame.
Talonflame @ Choice Band
Ability: Gale Wings
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Brave Bird
- Flare Blitz
- U-turn
- Roost
If you want to only crush things, this is this best set to my advice, sadly it has no more attack moves, so the fourth slot has to be a status move, and I think that Roost is the best, but you can also run Sleep Talk to avoid Spore, since Talonflame can easily switch in on all the users of that move (Breloom, Mega-Venusaur, Amoonguss)
Talonflame @ Sharp Beak
Ability: Gale Wings
EVs: 120 HP / 252 Atk / 136 Spe
Jolly Nature
- Brave Bird
- Flare Blitz
- Roost
- Swords Dance
Honestly this is my favourite set, you boost with Swords Dance once you eliminate all the Pokémons that walls it and then you destroy the entire team of your opponent thanks to Brave Bird and Flare Blitz
Talonflame @ Leftovers
Ability: Gale Wings
EVs: 248 HP / 252 SpD / 8 Spe
Careful Nature
- Brave Bird
- Taunt
- Roost
- Will-O-Wisp
Talonflame @ Leftovers
Ability: Gale Wings
EVs: 248 HP / 252 SpD / 8 Spe
Careful Nature
- Bulk Up
- Brave Bird
- Roost
- Taunt/ Will-O-Wisp
These two sets are also worth to mention, the first one is a really good stallbreaker thanks to Taunt and Will-O-Wisp
The last (but not least) is similar to the stallbreaker one, but it runs Bulk Up to gain physical bulk and boost his attack, and when you powered up enough, you can start sweeping with Brave Bird