Love your ideas, Phantasm!
All it needs is a relation to (or a reflection of) Batman as a character and an overall point to make, philosophically and emotionally. Just overlay that onto your ideas, which should be fun with the villains you chose, and I'd watch all of those happily.
Here's an example of relating Batman into the fold, keeping everyone relevant to each other thematically: You could use the concept of Sionis going around in a frightening mask to do things beyond his reach as a normal man, or Clayface disguising himself or shapeshifting, to comment on Batman's use of disguise and fear - including his false Bruce Wayne persona.
Really play up the psyche of that, the obsession. Show how it can be used for good or for bad, and how the city perceives Batman as perhaps scary or potentially evil because of his appearance and methods. This keeps him tragically untrusted despite the good he's trying to do. Kids see a menacing black skull and run the same way they would run from a menacing black bat face.
Condensed: We see a parallel of Bruce Wayne in Clayface, and a parallel of Batman in Black Mask.
This can go deeper of course, add layers. Such as Sionis being a rich kid that inherited and built a lot of wealth, but directed that wealth toward the opposite end of the spectrum than Bruce did.