The two films will be Captain America: Civil War and Ant-Man. The Civil War pack will be available at the main game's launch on January 26th, and includes 9 characters that are also able to be used in the main game. There will be Captain America, Iron Man (in the Mark 46 armor), Black Panther, Winter Soldier, Falcon, War Machine, Scarlet Witch, Crossbones, and Agent 13.
The second DLC, the one I am personally very excited for, is the Ant-Man level pack. This contains 11 new characters including both Scott Lang and Hank Pym as Ant-Man, Ant-Thony the flying ant, Cassie Lang, Darren Cross, Scott Lang, Hank Pym, Hope Van Dyne, Luis, Janet Van Dyne as The Wasp, and Yellowjacket.
At the end of the announcement of this being a Playstation timed exclusive deal, there was a little tidbit extra about a season pass and its contents:
"Keep an eye out for the season pass content that we’ll be bringing your way featuring classic comic content as well as content from Marvel’s Agents of S.H.I.E.L.D."Source [ Playstation Blog ]