That sounds like a good idea, actually. But one problem, how would they word it? 'Cause if you have no more Bakugan when it's your turn and nobody has three gate cards yet, then you get back all your Bakugan.
Or better yet “Play during a battle where you have 2 Bakugan in your used pile and your opponent has 2 Gate Cards in his used pile *INSERT SUPER EPIC EFFECT HERE*”