Either Secret Avengers, Thunderbolts, or just plain Avengers.

The Dark Avengers are usually save for a team that are Villains Based which this team isn't.

Secret Avengers maybe

Avengers

I feel like it could be Dark Avengers

Dark Avengers.

Again the Dark Avengers are for the Villain Team name not a Hero Team name, that's why they are call the Dark Avengers because they are a Dark Mirror of the OG Avengers Team.

Aren't the Thunderbolts supposed to be anti-heroes?

Yes but they aren't supposed to be Villains which the Dark Avengers usually are.

Besides The Dark Avengers is usually for Thunderbolt Ross team of Avengers that he is clearly setting up. Yelena and Bucky aren't going to be working for him after all lol.

Aye but some are villains

Former villains/antagonists.