Suggestions by @castermaster

Octavia Spencer

as Helga Hufflepuff in Founders

Score: -1

Dev Patel

as Godric Gryffindor in Founders

Score: -3

Keira Knightley

as Rowena Ravenclaw in Founders

Score: -2

Kelly Macdonald

as Rowena Ravenclaw in Founders

Score: -2

Henry Cavill

as Salazar Slytherin in Founders

Score: -2

Kate Winslet

as Rowena Ravenclaw in Founders

Score: -1

Angelina Jolie

as Rowena Ravenclaw in Founders

Score: -3

Vanessa Morgan

as Darcy in Winx Club Live Action

Score: +1

Danny Griffin

as Orion in A cuban girl's guide to tea and tommorow

Score: +1

Isabela Merced

as Lila in A cuban girl's guide to tea and tommorow

Score: +2

Lana Condor

as Vanessa in Across The 2nd Dimension: A Phineas and Ferb Movie

Score: +1

Zoey Deutch

as Candace Flynn in Across The 2nd Dimension: A Phineas and Ferb Movie

Score: +1

Jaren Lewison

as #108 in Celebs who could play siblings in a movie

Score: 0

David Henrie

as #108 in Celebs who could play siblings in a movie

Score: +3

Ansel Elgort

as Jake Peralta in BROOKLYN NINE NINE

Score: 0

Gwen Stefani

as #102 in Celebs who could play siblings in a movie

Score: +2

Ranveer Singh

as Amar in Divergent

Score: +1