Noivern is arguably one of the Pokémon most buffed by the Terastalization mechanic. Getting STAB on the ludicrously powerful Boomburst loses out only to Dragonite getting STAB on Extreme Speed. Exploud garnered fame in the 6th Generation for having no defensive answers between Boomburst and its wide coverage, and was largely let down by its poor Bulk and Speed. Not only is Noivern's Special Attack slightly higher, it is MUCH faster. Noivern's excellent Speed tier leaves Dragapult, Chien-Pao, Weavile, Iron Bundle and Flutter Mane as the only common Pokémon that naturally outspeed it.
Of course, Noivern is not Exploud and is let down in a few key areas. Scrappy was amazing on Exploud, enabling it to get away without having to run coverage for Ghost types and ensuring nothing was safe switching in, while Noivern has no such luck forcing it to run Dark Pulse for them and making prospective Choice Specs sets much weaker. Having to rely on Focus Blast for Rock types is a degree of unreliability that can be hard to stomach. Additionally having to dedicate your Terastalization to Noivern can cut down on your team's flexibility and can even outright lock you out of certain Pokémon like Pawmot.
Noivern is grateful that it is not Exploud as it is far from a one trick bat, having a healthy support movepool that makes it a flexible option for many teams.
Item Attached: Focus Sash/Covert Cloak
EVs and Nature:
4 HP / 252 SAtk / 252 Spe
Tera Type: Fire/Steel
A set meant for Doubles where Noivern offers excellent support and disruption. As mentioned before, the number of common Pokémon that naturally outspeed Noivern can be counted on one hand, making Noivern reliable at setting up Tailwind and shutting down opposing setups with a speedy Taunt that isn't Prankster Boosted and thus can't be stopped by Dark types/Tera Dark. Frisk further increases the utility Noivern offers, showing what items your opponent has. Knowing what item can be instrumental in figuring an opponent's set or knowing when they are running protective items like Covert Cloak and Safety Goggles to avoid moves that would be shutdown by them.
As for the offense, Noivern offers a fast Draco Meteor that will force your opponent to Terastalize or lose their Dragon while Super Fang is great in softening up bulkier targets it lacks the direct power to answer itself. Flamethrower is also an option as Terastalization coverage given how Fire resists both Ice and Fairy and offers fairly complimentary coverage with Draco Meteor.
Focus Sash is preferred for ensuring the Tailwind goes up despite faster attackers, though Covert Cloak is worth considering for blanking a Fake Out intended to stop Noivern from setting up.
Other Options and Preferred Partners
Tera Normal + Boomburst -yes it is that good, but should be run with a Ghost type or teammate with Telepathy/Protect to avoid friendly fire.
Shadow Ball -Enemy Number One is Flutter Mane so coverage against it is worth consideration.
Flutter Mane & Chi Yu -Noivern's biggest issue are naturally faster attackers who can outspeed and OHKO it. Flutter Mane and Chi Yu have great matchups against opposing Flutter Mane, Chien-Pao, and to a lesser extent, Iron Bundle especially when Noivern's Tailwind is up, which makes them far more unmanageable than usual.