The roster has three different kinds of information:
Base playable roster: Batman, Robin, Batgirl, Catwoman, Nightwing, Talia al Ghul, and Jim Gordon.
DLC-linked playable content: The Joker and Harley Quinn through the Mayhem Collection lane.
Progression system: every playable character has a distinct progression tree, but full tree details are not ready to treat as a build guide.
Read the weaker fields as practical cautions:
If only the character name is listed, treat the row as playable roster proof, not as an ability guide.
If Batman tools are named, you can plan around Batarangs, Batclaw, and Cape Line, but not a complete gadget tree.
If a row says Mayhem Collection-linked, verify editions and bonuses or updates and DLC before assuming access.
If a favorite character is not listed, treat that as "not supported by the current roster material," not as proof of a future plan.