Quote Originally Posted by Kelb_Panthera View Post
Special: The character must have single-handedly slain a juvenile (or older) red dragon
The key word here is "slain". It doesn't say "defeated" or "fought and slain" or anything of that nature. You can bring as many allies as you want, so long as none of them do anything that could kill the dragon. In fact, you don't even have to participate in the fight - after your allies knock it out, you can coup-de-grace it at your leisure.