This page is our investigation of cross-play feature in game called Rocket League. We also want to mention that - we always put manual efforts to find the precise, valid, and what is more important official information about different game features without using AI.
Games can have different cross-play combinations, for example the game can have cross-play between PC, Playstation 5, Xbox X|S, but not between old generations like: Xbox One, Playstation 4, PC. To avoid any misinterpretations, we group them into so called "cross-play variations".
Any store inside the cross-play variation have a cross-play only with a store in the SAME variation. We also want to notice, that we put into variation not platform, but store + platform. That is required because some games, for example, can have cross-play between a Playstation 5 and Steam, but not Playstation 5 and Epic Games.
Rocket League didn't have cross-play at release; it was added later, and on Jan 14, 2019, it was officially announced that the game supports cross-play between all available platforms, so players on PlayStation, Xbox, Nintendo Switch, PC (Steam and Epic Games Store) can play together. You can read the source by yourself here, or just check a screenshot below
We also want to pay attention that the article, which we set as a proof, does not contain information about the Epic Games Store. The game supports cross-play with this store, but because Rocket League is owned by Epic Games, and even their website is part of the Epic Games Store, the article authors decided not to include their store in the article