* Dan Kuso: While Dan is the protagonist, he's also known for infiltrating enemy territory and using deception to get information. This is especially true during his battles against the Vexos and the Vestal.
* Marucho: Throughout the series, Marucho uses his technological expertise to gather information and manipulate situations to his advantage. He's often seen as a strategist and planner, utilizing his knowledge to help his team.
* Runo Misaki: While not a traditional "spy", Runo is skilled in combat and uses her quick wit and charm to gain advantages. She's capable of infiltrating enemy territory and manipulating people to achieve her goals.
* Alice Gehabich: This character from the Gundalian Invaders arc, is a clear example of a spy. She is assigned to gather information about the Brawlers and their Bakugan, and uses deception and her position as a rival to accomplish her mission.
It's important to note that these characters are all aligned with the Brawlers and ultimately fight for good. Their actions may be considered "spy-like" but they are not actually spies in the traditional sense, as they are not working against their own allies.
Do you have any specific character in mind that you think might be a spy?