> > I just read a recent issue of JLU with him in it with Booster Gold, recalled a JLU ep with BG, wondering if they also did one with BB.
> >
> >
> > - Rodimus
>
> No. The character was never ever considered.

They wanted to use the character, but DC/WB wouldn't let them for whatever reason. Certain characters were off limits to the show, such as the Batman characters (other than Batman), Aquaman, the Teen Titans, the JSA, and various others.

http://dcanimated.wikia.com/wiki/Bat-Embargo has information on that. From that page:

"I think (Nemesis) was on a list of 'rights-available' guys that DC gave to us. And he is a unique 'type,' so we said, 'What the hell, put him in the show, we need bodies.' I would much rather have had Phantom Stranger, Blue Beetle, etc, but they were off-limits for whatever reason.      ”

— Bruce Timm in DrawingBoard.org