Psyonix says you’ll be able to unlink platforms and turn primaries if you change your thoughts, but you won’t have the ability to link any platform you remove to another Epic Video games account. In terms of items in your stock, the characteristic will allow you to share all earned free drops, season rewards, shop purchases, Rocket Pass items, blueprints, and Rocket League-branded DLC. However, you can’t share platform-exclusive items and credits. You’ll be able to share Premium DLC Packs, as well, but Psyonix is working to make them accessible throughout platforms at some point.
In the end, the developer has clarified that you can only trade purchased items on the platform you bought them on to reduce the risk of fraud. You can’t hop onto Xbox to trade something you bought on PlayStation, for instance. You’ll also need at least 500 Credits to trade unless you’ve been playing Rocket League sooner than free to play’s lunch.