Old Friends, Old Enemies

Hello fellow wiki editors, M3 here. Now I'm sure you have watched most of the episodes in Beware the Batman. As a matter of fact, I do miss some of the old characters from other Batman media. I do notice that they re-added some of the old characters there. I was thinking, what would Batman's old friends and old enemies would look like if they make an appearance. That would be fun. That is if the company is willing to do this. What do you guys think? Who might make an appearance?