Michaelangelo looks like he uses his skateboard as a ranged weapon in a few special moves; Donatello has reach with his bo staff, but also seems to be a grappler; Raphael is a close-range fighter with a counter move; and Leonardo seems to split the difference between the other three.
Each turtle has their own unique movesets and special moves. The team comes as a single character and you switch between them by equipping their weapons—katana, bo staff, nunchaku, or sai—in the character loadout. In online and tournament play, each turtle is selectable on the character screen.
Fighter Pack 3 also offers The Atom and Enchantress. It's currently available on Steam, the Xbox Store, and the PlayStation Store for $19.99. Those who own Injustice 2: Ultimate Edition already have access to Fighter Pack 3.