Ok, first things first, that Talonflame set would need to change; Banded acrobatics is never worth using, as holding the choice band halves the power of acrobatics. If you want acro, then run either no item, or a lure set with natural gift grass/ice/ground as well. Plus Banded Talonflame is not anywhere near as good as it was back in XY, due to the increase in bulky Lando/rocky helmet Chomp. A more viable set these days would be:
Talonflame @ Sharp Beak Ability: Gale Wings EVs: 252 Atk / 4 Def / 252 Spe Jolly Nature - Brave Bird - Flare Blitz - Swords Dance - Roost
Or
Talonflame Ability: Gale Wings EVs: 248 HP / 252 SpD / 8 Spe Careful Nature - Acrobatics - Roost - Bulk Up - Will-O-Wisp
As these let you set up to beat opposing threats, and after a turn or two easily out power Banded Flame.
Given that you already have a fire and a water Mon, a Fire water grass core can easily follow. Because nothing on your team thus far really likes scarf T-tar, or bisharp I would suggest adding Breloom
Breloom @ Life Orb Ability: Technician EVs: 252 Atk / 4 Def / 252 Spe Jolly Nature - Spore - Bullet Seed - Mach Punch - Swords Dance/Rock Tomb
Breloom also gives an answer to bulky waters like opposing Slowbro, and spore really helps to neutralise some threats.
With the four pokemon you have so far you are pretty weak to Sand teams and fairies, and also have no real answers to lati@s after gardevoir gets weakened, so I would add skarmory
Skarmory @ Leftovers Ability: Sturdy EVs: 224 HP / 32 Def / 252 SpD Careful Nature - Iron Head - Spikes - Roost - Whirlwind
At this point the team has something of an electric weakness, so a ground type would be pretty handy; Excadrill fits on the team decently well, as it offers fairly good synergy with Talonflame and Slowbro, and with a scarf gives you some much needed speed, and a way to deal with charizards
Excadrill @ Choice Scarf Ability: Mold Breaker EVs: 252 Atk / 4 SpD / 252 Spe Jolly Nature - Earthquake - Iron Head - Rock Slide - Rapid Spin
The hazard control from rapid spin is also useful for talonflame