The UFC 4 game does not support crossplay, much to the disappointment of gamers around the world.

Is UFC 3 cross platform Xbox and PS4?

There are cross play between PS4 and pc. But no between ps and XBOX, and it will not be in near feature.

Can Xbox and PS4 play together?

PS4 Games With Full Crossplay Support

The following PlayStation 4 games currently support crossplay functionality completely – which is to say that the players from at least all three major online gaming platforms (PS4, Xbox One and PC) can play against or with each other without issue.