Canon scope: Black Meridian infiltrator. Several transformation rules are still undecided.
The Two of Diamonds is a shapeshifter working with Black Meridian. The role depends on getting into places where an obvious armed attack would fail. Disguise, misdirection, and the threat of mistaken identity make the character useful to Joker's organization.
An assumed appearance should never be mistaken for a locked true form. The character's own definitive look has yet to be designed.
Shapeshifting is established; its precise mechanics are not. Copy limits, duration, voice imitation, memory access, and magical-signature replication all require separate decisions.
In particular, taking someone's appearance does not automatically grant that person's memories or powers. Any later scene using those abilities must be supported by a new canon decision first.
Confirmed: Rank Two of Diamonds; affiliation Black Meridian; shapeshifting; infiltration and identity manipulation. Unresolved: True appearance and the full transformation rules.