76ers: probably get the best end of this deal, getting the All-Star level player for Simmons as well as some key depth pieces for the postseason. They get a lot of lineup flexibility too; they can either start Maxey/Curry/Brown/Harris/Embiid with Barnes as the 6th man or Maxey/Brown/Barnes/Harris/Embiid with Curry as the 6th man depending on what they feel they need more of. They could also try dumping Harris somewhere to have more cap flexibility and getting a better-fitting player in return but getting rid of that deal will be easier said than done

Wizards: It's been rumored more than often Beal may not want to come back and head to another team. In this case, they do their franchise player a favor in sending him to Boston to play with his friend Tatum, which is where he'd likely go in FA anyway. They also get off of that ugly Bertans contract (while taking on half of a season of Thompson) and a few expiring deals for another shooter to replace Beal and some younger players and a solid haul of picks. For now, they'd run their same starting 5 with Hield in for Beal unless they would do more selling at the trade deadline

Celtics: They get a deadly duo to contend in the east for the next few years with Beal and Tatum. They also clear out Horford's money to help them get below the luxury tax and replace it with Bertans. Getting another shooter in Korkmaz also helps some of their problems too. They'd run a starting lineup of Smart/Beal/Richardson/Tatum/Williams with Korkmaz and others coming off of the bench after this trade. JB will be missed, but upgrading to Beal over him is worth it for them

Kings: They finally find a way to land Simmons without getting rid of Haliburton or Fox. They give up a number of other assets and players to do so but they are able to form a new lineup suited to most of Ben's strengths while making a playoff push in the West: Fox/Haliburton/Green/Simmons/Horford. This would be the first of 2 moves for the Kings since Holmes would be getting moved out in a separate trade for additional shooting and/or picks if they wanted to make a bigger splash down the line