While it has been previously revealed that you will be taking control of heroes from various Tales games and as such will be pitted against the bosses from these games, the latest issue of Jump revealed that through completing certain conditions you will be able to take control of these baddies as playable characters. For example, Duke Pantarei from Tales of Vesperia will appear as both foe and playable character within the game. Also recently released by Namco Bandai are two character trailers for Tales of Rebirth characters which I have shown below:
Tytree Crowe
Veigue Lungberg