Batgirl was essentially Batman's sidekick. She was romantically paired with either Batman or Robin (or Nightwing, same thing), depending on which canon storyline you follow. After a brutal beating by The Joker, she was left paralyzed and was figuratively reborn as Oracle (or The Oracle). A whiz with electronics and sharp as a tack, she joined Black Canary to form Birds of Prey, with Huntress and other heroes over time.
Barbara started as, no surprise here, a DC Superhero Girls Batgirl figure. I'd initially wanted to do a simple headswap, but Batgirl's neck was far too long to work, too long even with the original head. I had to considerably cut down the neck, leaving the internal plastic rod to hold the head on, intact. The ball at the end of the rod was cut off mostly, leaving a slight flange of plastic. Then, I simply wrapped the internal rod with tape to get a desired thickness to allow me to put April's head onto the body. I'd devised a pair of paper clip eyeglasses, but they simply would not stay on, even with glue.
Her wheelchair is Professor X's, with the two nubs of plastic on the back cut off.
Initially, I tried using some Gorilla glue to build up the neck stem, but that fared badly, with the glue seeping onto the back and getting caught in the head, even though it had been cured. I eventually gave up that route and went with the simpler, tried and true, method of wrapping the post with tape. Fairly effective, it can be removed at a later date, should I decide to put another head on the figure.
I've seen a lot of customs of Oracle done where she's wearing civilian clothes. Those really do look great, but it wasn't where I wanted to take her. I wanted this to show off where she's been, how she's changed, and who she is now. Without the DC Superhero Girls theme, Batgirl's outfit looks a lot less like tights and more like the athlesiure clothes that most young adults wear. I did repaint her yellow Bat logo black, to change things up.
To be brutally honest, since she's working with Black Canary, Barbara/Oracle isn't really working alone, and doesn't have a solo career, but, she's a hero in her own right, more so now than when she was Batgirl. As a disabled person myself, I really love that Oracle can be a hero, do her own thing, and not feel confined by her limitations. She's as much a hero as Robin/Nightwing, Batman, and other, non-powered heroes.