A Coolio Scarecrow would also have been plenty nutty and would’ve fit in perfectly with the weird tone of that Batman series.
Unfortunately, Batman and Robin was, well, quite bad, and the fifth installment in that Batman series never got made.
Coolio told the Burleson Star (via THR) that Schumacher had promised him the villain role in the Batman movie that never happened.
Joel Schumacher revealed back in 2015 that he had also courted Nicolas Cage for Scarecrow, and that he’d wanted the fifth Batman to kind of tie up the series, with Scarecrow and Harley Quinn teaming up to drive Batman insane.