Cartoon Network has released a preview for the first episode of season 3; Omni-Copped. It features Ben looking through his new aliens before transforming into Slapback and testing him out.
Gwen and Two Slapbacks in the Omni-Copter
It reveals that Slapback is large but not very strong but is able to duplicate into two smaller, stronger and heavier versions of himself by falling on his back. He also replaces Grey Mattter in the Ben 10 reboot, and shares the same voice actor; Todd Haberkorn. Check out the preview below: