What is the highlight around one of the attribute bonuses on the Gate card for?
You can safely ignore that… for now… That is called the “highlighted bonus” and there will be cards that come out in the future (as well as Bakugan) that will use that number. When playing a collectable game like Bakugan, things will get updated from time to time, and some things that might not currently make sense will get updated to keep the game fresh and exciting.