Allen will become trade elligible in January, by then I think the Kings and Cavs will both be ready to make some changes in order to remain competitive in their respective conference. Garland might also request to be traded as previously stated by his agent.

Cavs improve frontcourt fit and playmaking issues. Right now their frontcourt lacks rebounding and offensive creation and production. By acquiring Sabonis they get their hands on pretty much THE GUY for those departments besides jokic. Johnson adds Elite Shooting, size and good Defense (especially in a system with other Elite defenders).

Kings go for a more traditional guard-center pairing in Fox & Allen. Being very athletic he definitely fits the mold of their Team. His great rim protection, shot blocking and Elite rebounding would generate even more Transition opportunities for the Kings. They also Bring in DFS who had a couple of bad-ish season in Brooklyn, though I firmly believe a new surrounding would do wonders for him. The prototype of a 3&D wing fits great next to the Kings on-ball Players. Fox, Monk and Derozan shot creation would provide him with great looks. Being able to guard both SF and PF comfortably he makes for a great fit next to Derozan.

Spurs acquire garland, whom they have been linked to frequently. Him and castle are definitively an exciting backcourt pairing. Im not sure of the long-term fit however, mainly because the Spurs Vision in Terms of roster building is not very clear, as of now.

Nets sell some of their proven Players for a lot of untapped Potential in vassell. His development came to a bit of a halt in San Antonio due to the arrival of Wembanyama and Star upside is questionable at best with him, non the less he is still pretty young and getting the ultimate Green light from the Nets might just rejuvinate his progress.