The Main villian of the movie was going to be TwoFace, ala Harvey Dent
-How i know this? Max Shreck's role in Batman Returns was originally written for Dent, but WB thought Burton's TwoFace was going to be to gruesome for children. The taser for Catwomen was going to cause his burns.
TwoFace would had been play by Billy Dee Williams who only signed on in 1989 b/c he knew his character turns into TwoFace and would be in later sequels. Plus he is a great actor and would had pulled this off nicely.
Catwomen/Selina Kyle was never set to return. Burton wanted us to just know she is out there some where and has "1" life left. She may have returned in a fourth, fifth or spin off if Burton continued that long.
The Riddler (Robin Williams) was in this movie. His character was very dark, unlike Carry. He wasnt in spandex. He was designed to have a dark green suit with one Question Mark on his tie and wore dark Purple Shades. His role in the movie was going to be that of Bruce's shrink, but becomes obsessed with him until Bruce decides that he dont need theorpy and that Edward should leave him alone. This infuriates Edward who sets out to destroy Bruce, but knows he must defeat Batman as well. So he set riddles up all over town for Batman and sends Bruce his own little riddles for him to figure out. But he would not team up with TwoFace. He would be just a distraction for Bruce who is trying to fight/save Harvey.
Gordon got alot more time in this one then the first two together. While his role would not come near Gary Oldman's in Begins, since Gordon was friends with Harvey, he was much more involved this time around, says the writer from Batman Returns.
Dr. Chase Meridan was a character in Burton's movie, played by Rene Russo. She wasnt necessarily a love intrest, but a tease in a game of tag with Bruce/Batman but ultimatley gets deeply involved when Riddler stumbles upon her and see's her as a threat as she helps the police find him and solve his Riddles with Batman.
Alfred was not suppose to die in this one, but rumors of Harvey finding Batman is Bruce (ala end of Batman Returns) and killing Alfred was said to be an option for Burton, but like Michael Gough and his character so it wasnt set to happen.
Harvey Dent/TwoFace was out for revenge for people he felt were "responsible" for his accident and for the way Gotham is today. So Burton was going to have him kill the Mayor, and try to kill Gordon, but only shoots him. TwoFace would also try to kill Bruce/Batman since he knows the truth and would blame him for not saving him and stopping Selina Kyle.
Remember, these are all things that werent set in stone, but we suppose to happen as Burton and company thought ahead and may have even written a rough script somewhere. This was what Burton wanted to do, but WB thought differently.