Holder Carver (Sleeper- Wildstorm)- Near invincible, feels little pain and has a mission-based objective working method. Is probably a far more effective team assasin than Wolverine could hope to be, with 1/10th of the baggage.
Green Lantern Alan Scott (DC)- All the powers of a Green Lantern without the problems of working for Oa. A legendary figure, he represents the history of heroism.
Black Canary (DC)- Great Martial Artist, sonic scream and a long time team player. Would Partner well with Carver on mission based adventures. Also prevents the Justice Avengers from being a total sausage-fest.
The Flash Wally West (DC)- You need a Speedster, and this was that guy for years on end. Probably the only sidekick to successfully succeed his mentor in comics, Wally has all the ability and little to prove.
Hank McCoy (Marvel)- Science-guy combined with incredible agility. Hank has been a team player since the early days of the Avengers, there are few who can match his experiance in teamwork and problem solving.
Genis Mar'Vell (Marvel)- Cosmic-guy. I figure a cosmic-guy beats a magic guy and Genis, whilst bringing a certain amount of insanity on occasions, was probably one of the most powerful individuals in the Marvel Universe. He seems to be more mentally stable in a team environment without Rick Jones in his head.
Blue Beetle (DC)- Batman without the broodiness, Ted brings wealth, technology and great skills of deduction to the team. Unjustly slaughtered and replaced with someone who has yet to aknowlage the existance of the lineage of the name, Blue Beetle deserves another chance.