http://www.saiyanisland.com/2016/02/vote-for-naruto-one-piece-fairy-tail-hxh-more-in-new-game/
You can pick two series to crossover. It is interesting since fairy tail can be included too. They haven't said what type of genera is though, hopefully it isn't a baseball game.
I'd like to see:
Naruto x One Piece
Since fans get into fights of which series is stronger or if Lufy could beat Naruto
Bleach x JoJo BA
Just for theme matching
One Punch Man x Hunter x Hunter
Hunters vs Heroes
Fairy Tail x Magi
Just because both have wizards