Mondavarious, owning a theme park, Spooky Island, takes everything of it that he owns there very seriously. As the real Mondavarious at the end of the film, he is shown to be very thankful, when thanking Shaggy and all of Mystery Inc for setting him and all of Spooky Island free from the tyranny of Scrappy Doo.
For Scrappy Doo in disguise as the robot version of Emile Mondavarious, he pretended to be innocent during Mystery Inc's. vacation at Spooky Island. He told them that the college students are acting "strange" as they are departing from the island. He mentions that he himself is "terrified" of what is going on in the park. After Fred revealed the 3 suspects behind the monster attacks and the Daemon Ritus ritual. Fred pointed out that Emile (robot) is the 3rd one. He is hesitated at first and asks why he would be a "suspect". Fred tells him that it's because he kind of "creeps" him out. To which Emile accepts, but says it rather sarcastically.
Emile Mondavarious is a slim, middle-aged Caucasian man with fair skin, short black hair and brown eyes. Whilst being Scrappy's prisoner he had longer hair and a beard. Later, as Scrappy was being arrested and all of Mystery Incorporated were celebrating along with all of Spooky Island, he was later seen to having his hair cut back to how he likes it and his face clean shaved.
As a Robot version
The Mondavarious robot was designed to look exactly like the real one. When the gang first met him, he was wearing a black jacket over a Hawaiian shirt, a Spooky Island T-Shirt, grey short pants and a pair of sandals. During the ceremony ritual, he was wearing a long blue coat with small glowing silver diamonds on the outside. It also had silver patterns on the chest area. He also wore a blue suit underneath, along with a white shirt. When using the Daemon Ritus, it was attached to his chest. After he got knocked out by Shaggy (who was hanging onto a pincer claw), he would be unmasked by Fred and was revealed to be a robot operated by Scrappy-Doo from within the middle.
Role in the film
He is first seen greeting the gang to Spooky Island and explains to them that an evil spell is being cast over the students which caused them to behave in a violent or negative way.
Then, he is next seen when the gang return back to the hotel and they conclude the three suspects with one of them being Mondavarious himself. Mondavarious is present when N'Goo Tuana is playing the piano before the demons break in and abduct him along with Fred and Velma and most of the tourists.
He is later seen when the guards bring Scooby into his office where Mondavarious believes Scooby of him seeing Mary Jane as a demon in disguise and convinces him to be the sacrifice, which Scooby accepts.
Later on, he is next seen using the Daemon Ritus and placing it on his chest just as N'Goo takes out Scooby's soul, until Shaggy intervened and knocked Mondavarious aside, whilst letting Scooby's soul return to his body. When Fred and Velma discover a small cut on Mondavarious' jawline, they realize that he is a man and the mask and removes the face to reveal that Mondavarious is a mechanical version which is operated by Scrappy Doo - who turned against the Mystery gang for kicking him out due to his annoying behavior and vowed to get revenge.
After Scrappy Doo is defeated, Shaggy then hears a clanging noise from a manhole lid, and soon finds the real Mondavarious inside the manhole, with a beard grown and his hair grown longer. The real amusement park owner explains to Shaggy that Scrappy Doo traveled to Spooky Island and abducted him by imprisoning him in the manhole while Scrappy develops a mechanical replica of Mondavarious and controlled the island, as well as luring the Mystery gang to the island.
He is last seen (with his hair trimmed and had a clean shave) watching Scrappy, N' Goo and Zarkos getting arrested and watching the Mystery gang fully reunite.