First time through I saved all guests. Algus is nothing. Save Mustadio! I mean honestly, I have a gun, so I'm going to go--towards the enemy? Considering Agrias doesn't help the situation at all, that leaves things up to your other two characters and Ramza. Much tougher fight, because Protect/Shell/Cure are absolutely essential until you take out the archers and mages that threaten Mustadio. Golem/Silf/Moggle works well, but so early in the game its unlikely you'll have the MP for it, or the JP to get that many Summoner abilities.
RIP Gaming Lounge
Current games: Beyond the Beyond