After overhearing on the forums that you can hunt metal king slimes from level 1, I decided to give it a try as George is rather proficient with Thunder Thrust. The main difficulty is slugly betsy / moai minstrel allies. I've asked for advice on the forums, and learned that Thunder Thrust is rather effective against these enemies (especially metal slimes) and that Marcus and I would be very busy with resurrection and healing.

It's going very well so far. Marcus has even gotten two metal king slime kills with Pressure Pointer.

I still haven't found out whether it's better to get someone to super high tension when fighting high-stamina monsters. Jasmine and I decided to see just how much damage she can do in one hit:

annihilator127 eggs Jasmine on with a rallying cheer.
Jasmine's tension increases to 100.
Jasmine achieves a state of super high tension!

Marcus casts Midheal.
Marcus recovers 245 HP.

Jasmine casts Kafrizz.
Does 2160 points of damage to the slugly betsy.
The slugly betsy is defeated.

annihilator127: Holy crap!
Jasmine: Now that is a burn.

By the way, if any of you other GameSpot members are reading these, please feel free to post in the comments and say hi.