Well, three are destroyed with fire, but I don't think the E4 has any fire on them at all, save Shauntal and her annoying Chandelure. Evolving Pawniard and giving it a good dark move should be enough for Caitlin.

I'd scrap either Ferrothorn or Throh for a psychic or flying type for Marshal, but if your Darmanitan is enough brute force, he shouldn't be a problem.

More with Darmanitan, if it doesn't know any Fighting moves, teach it some; Throh probably won't last very long, but I haven't actually used one. If it's reliable, keep it, otherwise get something that can learn a Psychic and Ice move (Ice for after the E4. You'll want it for Ghetsis).

Shauntal should be fairly straightforward with a Carracosta.

Now, if this is the rematch, the above changes should still apply, though Ice is more recommended (then again, it's only for the Champion and I haven't really fought a threatening Druddigon before).

Golurk seems like a nice option to replace Throh. It has a ridiculously expansive movepool, and can give you Psychic, Ice Beam, Hammer Arm (since you don't need to worry about speed with Golurk), and Shadow Punch/Ball. Ridiculously, that moveset should cover most all of the E4 + Ice Beam.

My Throh has actually been fairly reliable throughout my adventure. He's powered me through several gyms. And my Darmanitan plowed through the last two gyms no problem, so he's doing well. Sheer Force, Charcoal, and STAB are godsends.

I actually have a Golett sitting around in my box right now, so I should get on evolving him, Pawniard and Tirtouga, then.

Big thanks, man.