This All-Stars Battle Royale video game is only playable on and available for PlayStation 3. The best part though is that when you buy this game, you get a code to unlock the game on PlayStation Vita. This is called a cross-buy.
Another nice feature is that you're allowed to play any character you want. Furthermore, you can cross-save and cross-play between the PlayStation 3 and Vita.
Online you need at least one more person to play the game, you can't have more than 4 players connected at the same time. During a normal game-play you can play alone or with 3 more people.
The All-Stars Battle Royale game allows for players to video chat. However, this feature requires a headset that is not included.