Sharp Beak Talonflame is the most optimal choice on an SD set apart from Leftovers. You will be using Brave Bird as your main attacking move almost all the time, thanks to Talonflame's ability, and Flare Blitz will only be an option vs electric types or Steel types. The main focus to use Sharp Beak is to OHKO Thundurus with a +2 Brave Bird after it takes SR damage, as well as powering up your "main" STAB move. This means, if EV'd correctly, your talonflame will never get "crippled" by Thundurus' Thunder Wave after it has at least set up 1 SD, which isnt very difficult to do.
However, this talonflame is incorrectly EVd for such situations. A spread of 88 HP / 252 Atk / 168 Spe with a Jolly nature ensures that Thundurus may never TWave you again, as well as other valuable feats; outspeeding Scarf Magnezone, and revenge killing Raikou with Flare Blitz. You can potentially run Max speed to ensure Weavile may never pick you off with an Ice Shard, but you have Azumarill for such matters. 168 Speed ensures you outspeed up to base 115 pokemons (specifically Raikou), and covering any other threat past that apart from Weavile is silly, since the superior option will always be Brave Bird, a move with Priority.
Also, run Timid Starmie. It needs all the speed it can get in this hellhole of a speed-infested tier. TWave is a wasted moveslot, and a coverage move in TBolt, or STAB move in Psyshock/Psychic is preferred. Run Analytic as the ability, to pack a punch vs common switch ins.
