Marco is a self-obsessed bully, who has a history of being the biggest bully in Los Volmos. He bullies the Rowdy Reds out of their park with a Pyrus Cyndeous, despite Cyndeous wishing to do the right thing. He takes over the park in Costero Canyada from the Rowdy Reds, which attracts the attention of Max, who is in awe of Marco seemingly raw power. Marco constructs a large stage for him preside over the park, as well as several monuments to himself, and uses Max as his personal servant. He refers to the park as his "kingdom", and uses Cyndeous to intimate anyone who would challenge him. He tricks Cyndeous by exploiting his lack of knowledge about Earth and convincing him that Marco's cruel tactics are "just the way the world works here".

After trapping Trox and Gorthion defenseless in a pit and striking them with Cyndeous' Sword Blade, Marco turns his sights on the brawlers, and orders Cyndeous to attack the Awesome Ones and Rowdy Reds. This command goes against Cyndeous' morals, and causes him to fly into a fit of rage, attacking randomly. One of these attacks heads for Marco and Max, but Drago protects them. Instead of recognizing the sacrifice Drago had made to protect him, Marco yells Cyndeous on. As Cyndeous snaps out of his rage, Marco only commands him to attack more, which causes Cyndeous to direct tell him he will longer be obeying Marco's cowardly orders. This upsets Marco, causing him to yell and insult Cyndeous. Dan, seeing his previous actions that day reflected in Marco, pushes him over, and ends the brawl. Later that day, Cyndeous ends his partnership with Marco.

(Source: Bakugan Wiki)