Decapre first made a cameo as one of the Dolls in Juni and Juli's pre-fight animation against Cammy in SFZERO3. She had more exposure in UDON's Street Fighter comic, where she uses claws similar to Balrog (Vega in the US). In the game, she instead uses blades made of concentrated Psycho Power, comparable to that of X-Men's Psylocke.
On the plus side, though, story-wise, giving prominence to this "clone" character finally makes way for a story long untold: the story of the Dolls. I'm actually looking forward to the OVA for this one.
The game will be released as a stand-alone game or as a downloadable update on June.