Solo Shuffle
Solo Shuffle is the solo queue for 3v3 Arena with 6 rounds for the entire match. It'll find two healers and four DPS and with each round after the first, it'll "shuffle" the teams to be grouped with other players in the match.
Since its debut, it has grown in popularity and even received its own esports tournament, Solo Shuffle Showdown.[1]
Rated
Introduced in patch 10.0.0, Rated Solo Shuffle will have a rating tracked for each of their character's specializations. Additionally, just like in Rated Battlegrounds and Arenas, players will be able to earn seasonal rewards and achievements, credit towards Vicious mounts, weekly Great Vault progress, and 
[Conquest]. Cross-faction is enabled so Horde and Alliance can match together and play against each other.
Achievements, along with the Legend title and pennant toys, are tied to each season along with a 0.1% top achievement:
Patch changes
Patch 10.0.0 (2022-10-25): Rated added. 
Patch 9.2.0 (2022-02-22): Added.
References
- ^ Solo Shuffle Showdown Is Kicking Off Soon!. Blizzard Entertainment (2022-09-22).