I remember hearing about this a year ago and thinking "How the hell do you do a Bizarro Superman movie without Superman?"
The same way you do a Catwoman movie without Batman.
I can see a Catwoman movie working. Batman is not integral to origin and/or "mission".
However, considering the Bizarro is basically an imperfect copy of Superman, Superman would, logically, have to be in it in order for the titular character to be created.