Why Are You Shaking Your Digimon?

When I was younger, everybody had a Digimon virtual pet and would battle with each other. My little brother had the new Digimon Pendulum, I think it was called, and it seemed the more you shook it during the countdown before the battle the more chance it had of winning. When he battled someone who had the normal Digimon, they saw him shaking his Digimon Pendulum and started shaking theirs as well! But yours doesn't have the pendulum! It won't affect the battle if you shake yours!