First off, sweet project concept Claado has come up with here. I'm really looking forward to hearing the final result.
I'll get to work on my audition piece, though synth-free orchestration is a bit new to me. I would argue that certain limited synth work be allowed as (from what I understand) some of our greatest modern film composers use them to reinforce the orchestra, such as Hans Zimmer ("The Last Samurai," "The Lion King," etc.): my film composing god. However, he uses it VERY subtely and I can easily see synth work getting out of hand here so I'll respect your call on this.
As for drum kits, I believe you can get fantastic battle music without utilizing any type of rock or electronic-style percussion. Take the "Pirates of the Caribbean" OST (my all-time favorite film OST). All traditional bass drum, timpani, etc. but it still packs a great punch. Of course, if that's what you meant by drum sets, than disregard this whole paragraph. ^^
I'd love to take/collaborate on a battle theme if possible. ^^
....aw, we lost zircon? boooooo....