You'll want to run 4HP/252Atk/252Spe
You'll want to make sure the moveset is Acrobatics/Flare Blitz/Swords Dance/Tailwind
Alternatively, you'll want some bulky EV spread with HP and special defense with Acrobatics/Flare Blitz/Roost/Swords Dance
or maybe you'll want a bulky EV spread with HP and defense to make use of Bulk Up and Roost.
What are the benefits of Tailwind?
Sometimes, your Talonflame will drop below 50% HP and be useless if it switches out (as it will die to sneaky pebbles), so you can set up priority Tailwind to give your entire team +1speed to help revenge kill whatever took down Talonflame as well as boost for the next few turns.
What are the benefits of Roost with a defensive EV spread?
Sometimes, your opponent will bring in Pokemon that Talonflame can set up against. Roost will ensure you stay at high HP and better set up your Swords Dance or Bulk Up.
Swords Dance or Bulk Up?
This depends on whether you're going all offense or a gimmicky defense spread.
Once you've decided how you want to train your Talonflame it's time to get breeding. You will grab your Talonflame and make it fuck several Dittos until its offspring is a beautiful 31/31/31/xx/31/31 IV spread. Anything less is not acceptable.
Of course, if breeding is too much for you, you might as well do casual battling. Don't get me wrong, not everyone IV breeds, but it's a definite advantage.
