Brother MacLaren said:It's really hard; they're NOT extensions of the PC the way an arrow is. So I'll ask the DM what they'll do.
It isn't hard at all. Okay, sure if you want them to do anything other than kill your opponents then you have to be able to talk with them ala Speak With Animals. Other than that they just go and kill things that are trying to kill you. How hard is that? Dirt simple.
And what exactly makes the T-Rexs hindered by Protection from Good? Just let the Rexes chomp down and roll for them.
Summoned creatures attack your enemies. If you can tell them what else to do, they do it right away. They don't run away or show mercy or stop to have a snack in the middle of a fight. Unless you can tell them otherwise. It isn't hard work. They are YOUR spell effects. They are just as much your responsibility as fireballs and shadowy tentacles and other such and sundries.