He is very overweight and has metal braces on his teeth.
He is absolutely obsessed with Velma.
Skills and abilities
He made his own spider robot, so he has electronic skills (but not as much as his mother).
Scooby-Doo! Mystery Incorporated
The gang later had him help them by remote controlling the Krampus, his mother being freed earlier from jail in return. (Wrath of the Krampus)