I thought about Green Mask for Batman, but he seemed too super-powered (and in his Mark-2 version, was more of a Captain Marvel counterpart), and certainly Wonderman was a clear favorite for Superman (or even Wonder Woman, if you want to go there), but I really wanted to use Blue Beetle somewhere. Bouncer was on my list for Flash, as was the Lynx, but I went with the Dart just because his name at least sounds fast. I picked Stardust for Martian Manhunter over Lun-Ar mostly because Stardust was so darn alien, and like J'Onn, was more of a "pick any random power or gimmick per story" character--I'd love to hear the reasoning behind swapping him for the Atom, tho...