It won't be team vs team--it'll be player vs player, so each of us may fight a different element, or a few different elements, but each of us will know what element the opposing player is from. We should reserve our specific decks for the appropriate enemy--we'll have to guess what they'll be playing but we'll know what element at least half the cards are from.
That said, try to make yourself familiar with how to play the different decks or at least the ones you aren't familiar with--go to the trainer and grind AI3 for a while (or even T50) just to get a feel for when/how to play the card combos. You can even PVP duel each other and have one side be one of our decks and the other play an opposing type deck (shrieker rush, fractal devourer, blessed pegasus, fire stall, whatever.)