From the Super Mario Wiki
Sickobratz appears towards the end of the comic, in the Alte Oper where KKDU (in his human crooner disguise "Heini") is going to perform. KKDU's plan is to turn all humans into food and serve them to his alien fellows. Sickobratz is one of the cooks preparing the meal. He is also the one to inform KKDU after the meal has been prepared.
Sickobratz is a green alien with a reptile-like head and what seems to be whiskers. He is seen wearing a chef's toque. Some more aliens looking exactly like him are seen in the comic as well.