While it hasn’t been completely confirmed at this time, it has been rumoured by a tweet on Mortal Kombat creator (or should we say Kreator) Ed Boon, which linked to a wallpaper screenshot of Twisted Metal’s Sweet Tooth.
— Ed Boon (@noobde) December 7, 2014
While it’s nothing completely concrete at this time, it is definitely not out of the realm of possiblity. After all Sweet Tooth would fit right in to the Mortal Kombat world and Kratos was a playable character in the PS3 version of MK9. It’s no secret that the team at Neitherrealm were looking at exclusive fighters as well.