#4 Seth Rollins and Dean Ambrose
As Seth Rollins was embroiled in a feud with Dolph Ziggler over the Intercontinental Championship, he was lacking back up. Drew McIntyre had returned to ally himself with "the Showoff" but Rollins was still alone.
Dean Ambrose balanced the scales when he returned from injury to back his brother before SummerSlam. At the show, Rollins would recapture the title from Ziggler. Throughout the rest of the Summer and early Fall, the two former members of The Shield would oppose McIntyre, Ziggler and occasionally Braun Strowman.
During that feud, they traded the RAW Tag Team titles with each other to add another layer of importance to the feud. On the same night that Roman Reigns announced that he had to relinquish the Universal Championship and take some time off from WWE, Rollins and Ambrose won the titles again. But as we all know, that was the same night that Ambrose turned his back on Rollins.
After that, the two feuded with each other but eventually agreed to reform the Shield once it was evident that Ambrose would not be re-signing with the WWE. And with that, another team that held gold in 2018 was finished as a team.