Sigmario is a evil entity that was imprisoned inside Mario's soul after the events of Super Mario Sunshine.
Mario and Luigi: Dark Souls
He, along with Vuigi, were the main villains: They were responsible for the destruction of the soul star. It is also shown that they destroyed an entire galaxy using their great corrupting powers. They appear as the final bosses.
Mario Kart: Fireheart and Mario Kart: Icesoul
He appears as an unlockable character. His kart is the sprint E and his jet is the soar E.
In M&L: Dark Souls he used a moveset that mirrored Mario's, just as Vuigi's mirrored Luigi's.
Dark hammer: Sigmario and Vuigi both spin and using the hammer, hit the target; they pass it back and forth between each other until the combo is broken.
Poison mushroom toss: Using a poison mushroom launcher, they launch poison mushrooms into the mouth of the target. They throw it to each other until the combo is broken.
- It is unknown whether Sigmario and Vuigi are related or not
- one of Sigmario's quotes states that he has another form, though it is never shown