Marcus Smart cannot be traded this year since he signed an extension after August 6th.

Josh Richardson cannot be traded this year since he signed an extension after August 6th.

Juancho Hernangomez cannot be traded to a team aggregated with other players from his team because 2 months have not passed since he was traded for. He can only be traded away to a team by himself and other non-player assets from his team (draft picks, cash considerations, etc). This restriction expires after Nov 14, 2021.