Hard to say. I mean, if Transformers is on the table, just about ANYTHING is fair game. Peanut Butter and Jelly vs. Peanut Butter and Chocolate...Marvel vs. DC...I've even seen suggestions for Mario vs. Luigi, Star Wars vs. Star Trek and even Guns vs. Swords. Although Guns vs. Swords seems a bit..."mature" for this setup. Besides, there is the whole "21-foot rule" to consider.