Right now I have Lucina, Marth, Roy, and Zelda in Elite. I used to have Chrom and Robin too, but they dropped off when I wasn't playing the mode.
I find that getting into Elite isn't the problem, it's staying in there. Once I'm in Elite I seem to get a lot more matches against stuff like the Belmonts with 2 stocks and 3 minutes, who are just aiming to time the clock out and cheese wins in Sudden Death, or people with Final Smashes and stuff on. Which is lame because I figured once you're in Elite you should be able to get more matches against people with sensible rulesets, but instead it seems to be just full of people who only care about ranking up. The system just sucks and is a big reason why I don't bother with the mode often.