I have to say, having the dragon take leadership strikes me as pretty absurd. Any Great Wyrm is going to count as being such a high level, and has such a hefty CHA bonus that it'll be able to have a slew of cohorts in the high teens, level-wise. Which will make this exercise not a party vs. a dragon affair, but a party vs. another party + a dragon business. Which means that, to have a fighting chance at this, every one of the PC's will be well advised to take leadership and go for a decent CHA as well, and before we know it, it'll be a dragon + party of NPC's vs. a party + army affair... Then summoned solars and demons are going to come into play, with those nifty slaying arrows... We need some very clear restrictions on this, else it will get out of control extremely quickly.