Let's go through each team member in depth.
Looks just about solid. One thing that might be cool, though, is to take out Bullet Seed for Swords Dance. What with Greninja's Mat Block, and something I will include later, Heracross will get a myriad of opportunities to set up.
I advise using HP investment, or even Defense, rather than Special Defense. T-tar already gets a SpD boost from sand, and it increases your overall bulk rather than just one stat, but then again, that's just how I roll.
Keep in mind that T-tar's sandstorm will chip away at every one of your team members' health, so you might want to switch that to Unnerve. Oh, and what item would you be using if you ran Stealth Rock on T-tar? Cuz obviously you can't use it when you're running AV. Rocky Helmet might work.
One huge, huge, advantage Togekiss has over other Tailwinders is access to Follow Me. Follow Me is what I was referring to in the analysis for Mega Heracross, as drawing attacks to Togekiss will allow M-Hera to set up. So the changes I recommend are Wish -> Roost and Protect -> Follow Me.
Solid. Only possible change is Dark Pulse -> Scald / Hydro Pump.
I know you're probably going to disagree with this, but I say go for Defensive Talonflame.
Talonflame gets Will-O-Wisp, Tailwind, and Quick Guard. Tailwind boosts Speed which is just good, and Quick Guard protects the next Pokemon from Bullet Punch, opposing Brave Birds, etc. If you don't want another Tailwinder, you might run Bulk Up instead of Tailwind. With obligatory Brave Bird, I think it might actually work well!
Talonflame @ Leftovers
Ability: Gale Wings
EVs: 252 HP / 252 SpD / 4 Atk
Offensive Sylveon time!
With Tailwind boosting your speed and Quick Guard protecting you from Bullet Punch, Sylveon can run a good offensive set!
Sylveon @ Choice Specs / Life Orb
252 SpA / 252 Spe / 4 HP
-Hidden Power Ground/Wish/Helping Hand
Hidden Power Ground is preferred in that moveslot, but I understand you're breeding it so it may be difficult to get the right Hidden Power.
Hope I helped!