I haven't been trying to auto-farm any of the levels, but I've gotten through all but the last with this team:

-Navigator Eddie (Invisibility/Void) - Unsharded, but the troopers I have with Navigator are sharded and I use those sometimes
-Pharaoh Eddie in backup for revive/invincibility if needed
-Mystic/GRE for some magic damage
-Alliance General (All Health) - Fully sharded
-Gunner Pharaoh Dog (Invisibility/Energy) - Unsharded
-Gunner Golden Sun (Thief/Void) - Fully sharded

It can be a slog in this level since I don't bring any magus characters other than the Eddies, but the only time I've lost so far has been a time that the boss doomed 3 of my characters. It's pretty reliable for breaking the shields quickly and getting some hits on the boss.

Strategy is this: Have Navigators Fury chip away at the shield, give him an extra turn with GGS and then use the cannonballs to knock another 6 points off. Alliance General keeps the power flowing and keeps the Dragon King's fury repressed. GPD is there for healing/damage reduction/debuff removal. On the 2nd turn just use normal moves and the first shield is broken. This team generates enough fury to be in class advantage on most turns, and strategic use of Alliance General's power move can let you take a bite out of the bosses health.