>Shaggy is a stoner slacker wimp who has a dog.

No, Shaggy is a guy that solves mysteries with his friend Fred, Velma, and Daphne in a van that Fred owns.

Characters aren't just what they physically look like.

>If anything shaggy is his dad as he has the same hair style minus the beard. He’s also a good cook and smokes weed. There’s also a flashback were he meets norvilles grandmother and there’s a shot that look’s literally ripped out of the old scooby doo shows.

Yeah, that's also known as a "reference".

Also, why do we keep going back to this stoner thing? You realise that this is based on a children's cartoon right? Shaggy never actually smoked weed. It's not a character trait.

>Maybe if you watched the show you wouldn’t be the ass in this situation.

The fact that this characters personality is purposefully the opposite of what people associate with Shaggy (e.g., the stoner subculture) as a joke actually makes the opposite point of what you're trying to make.