On their twitter account, @Battle4TheGrid, nWay games announced 3 new characters available for free through DLC: Dragon Armor Trini from the MMPR Boom Comics, Udonna from Power Rangers Mystic Force, and Cenozoic Blue Ranger from the 2017 Power Rangers movie. Not sure if this is a new name to differentiate this Blue Ranger from the original, or if this is supposed to be the Blue Ranger from Zordon’s team (in the movie continuity, Zordon was a Red Ranger and lead a team of Rangers that included Rita as the Green Ranger).
They are part of the 1st update to the game, and are not part of the Season One pass. Those characters will be available via DLC at a later date.
Power Rangers: Battle for the Grid is currently available for X-Box One, Nintendo Switch, and the Playstation 4 (currently U.S. only).