Why don't we play a game of Chess with Different Armies with the same armies as each other? :D That will allow us to (re)adjust to the unfamiliar pieces so that the following game, which we can play with different armies, will be a fair competition rather than a determination of a person's ability to familiarize themselves with the pieces. That is assuming that one of us plays a familiar army the second game.
You pick the army, or if you'd rather, the armies. I don't believe we've played the Meticulous Mashers yet, though I can't remember for sure.