Blackwings are the Best Stun Engine

Why is that? They have a mess load of tricks when used together, but they can also stand alone.

-They have a Chainable removal card in Icarus Attack, which can be used to clear back rows, and that's important in a format without Heavy Storm.

-They have Black Whirlwind, which makes them all into Gadgets with higher ATK and effects.

-They have Tuners that can be Special Summoned (Gale, Breeze, Vayu (through Shura)), and a Tuner that can Special Summon Synchro Material (Blizzard).

-They have a way to Special Summon a Monster through cards like Solemn Warning and Royal Oppression (Vayu's effect).

-They have amazing battle tricks through Sirocco, Kalut, and Gale.

That's just inherently built into the theme. Using a certain play-style also removes the intended reliance on Special Summoning.

They also get around the biggest weakness other Stun decks have. Stun decks need to draw just a few Monsters while drawing a bunch of Spells/Traps to control the game. If Stun decks draw all Monsters, they lose. "Summon Banisher, pass," isn't exactly the strongest set-up.

If Blackwings draw an all-Monster hand, they can play out of it. If it's the right combination of Monsters, they could possibly push through a bunch of damage. That's because Bora and Gale Special Summon themselves, and Kalut acts like a Spell/Trap. Shura and Blizzard can also set up big plays on their own.

Because of all of this, Blackwings have no glaring weakness that you can take advantage of. They're all Dark, but Consecrated Light won't stay up for long with Book of Moon and Icarus Attack flying around. They need their Normal Summons to work, but they can just Chain Icarus Attack to your (Bottomless) Trap Hole/Torrential Tribute to clear out your cards. If you try to destroy their Blackwings with effects, they can Chain Icarus Attack, but if you try to attack over them, you might just be playing into a Kalut.

However, there are still good cards that you can use against them. Snowman Eater is a great choice, since they cannot Chain Icarus Attack during the Damage Step. Moreover, it's a 1900 DEF wall that they can't get rid of without taking a minus. What's more is that it's also good against other Stun decks and Gladiator Beasts.

Seven Tools of the Bandit can negate the Traps that they depend on, and Royal Decree can just shut them down if they drew a hand full of Traps. Although an odd choice, Bait Doll is also effective. You can force them to use an Icarus Attack when you don't have a field, so they'll have to destroy one of their own cards (they can destroy Bait Doll) in addition to tributing their Blackwing.

What's most important is knowing how to play against them. Their key card is Icarus Attack, if you didn't know already, so you have to play around that. If that means playing only one card at a time to the field, then that's what you should do. If that means baiting it out to make them waste it, then do that.

That doesn't mean that Blackwings are a good deck. They have consistency issues, since they only play like 10 Monsters that they use as beaters. Also, they don't have the speed that decks like X-Sabers and Lightsworn have. If Blackwings are playing from behind, Icarus Attack and Kalut may help, but they can't always have those cards when they need them.