This character is adopted when Robbie learns of the legend that the missing piece of the LazyTown Stone was buried in a pirate's treasure chest.
There is no selection process in the Rottenbeard episode.
However, the Rottenbeard costume can be seen in the disguise machine's furthest left chamber on the screen.
Other disguises seen in the machine's chambers are (right to left):-
Robbie wore: A pirate hat with skull and crossbones, an eyepatch, a mustache and beard (connected), a white shirt, a navy blue pirate's jacket, and pirate pants.
|Seson one: Rob U. Blind | Lazycus | The mailbox | Robbie's softball uniform | Sherlock Foams | Sportacus | The Birthday Fairy | Scotty the Scoutmaster | Dr. Rottenstein | Rottenbeard | The Dinosaur | Sir Rottenham of Robbington | The Rotten Kid | The gorilla suit | Soccerbot | Miss Roberta | Fordmil Meansbad | Santa Claus | The purple cow | Giant fruit and veg | Zobby|
|Season two: Johnny B. Badd | A purple bush | The Trash Man | Mayor Meanswell | The Ghost | The Snow Monster | Roberto the Great | The Shaking Cup operator | Rob R. Robley | The Purple Legend | Chef Robert | The gorilla suit (again) | Prof. H.R. Rottennen | The sticker vendor | The construction worker | Bob Wire | The Big Bad Wolf | Robbie's racing outfit | Sully Swingahip|
|Others: The aristocratic dress | The baby | The blue dress | The chicken | The court jester | Cowman | The crusader | Robbie's dressing gown | The nightgown and headdress | The silk clown | The white robe|