Suggestions by @fankid4

Tom Brady

as Frankenstein's Monster in Scooby Doo

Score: -2

eleanor rigby

as Theme Song in Scooby Doo

Score: +1

Basma Hassan

as Mummy in Scooby Doo

Score: +1

Antony Starr

as Dracula in Scooby Doo

Score: +1

Larry David

as Ghost Of Captain Cutler in Scooby Doo

Score: +1

Great Dane

as Scooby in Scooby Doo

Score: +1

Lizzy Greene

as Daphne in Scooby Doo

Score: +2

Millie Bobby Brown

as Velma in Scooby Doo

Score: +4

Louis Partridge

as Fred in Scooby Doo

Score: +3

Griffin Santopietro

as Shaggy in Scooby Doo

Score: +4

Joe Manganiello

as Deathstroke in The Villains

Score: +1

Aubrey Plaza

as Poison Ivy in The Villains

Score: +1

Martin Freeman

as Mad Hatter in The Villains

Score: +1

Hayden Christensen

as Riddller in The Villains

Score: +2

Timothy Olyphant

as Mr Freeze in The Villains

Score: +1

Dave Bautista

as Bane in The Villains

Score: +1

Daniel Radcliffe

as Penguin in The Villains

Score: +2

Michael B. Jordan

as Killer Croc in The Villains

Score: +2

Ian Somerhalder

as Hush in The Villains

Score: +1

Michael Shannon

as Black Mask in The Villains

Score: +2