Since Dragon Ball FighterZ is mainly a PVP game, then online multiplayer is a major concept for this game.

According to the French Gameblog in their interview with the producer, Tomoko Hiroki, they asked her whether if they are planning to offer cross-platform for Dragon Ball FighterZ or not, and her reply was "they may think about it if enough fans wanted that".

So, gather up! and lend us your energy!

Source:

http://www.gameblog.fr/dossier_1084_dragon-ball-fighterz-roster-mode-histoire-version-switch-la

Making the game cross-platform is completely possible, it has already been done for Rocket League, although the consoles can't get matched up together but PC players can get matched with both of the consoles.

Source:

http://rocketleague.wikia.com/wiki/Cross-platform_play