Suggestions by @nosetwice

Stan Woozle

as Weasel/ferret in Fictional animals by species

Heff

as Elephant in Fictional animals by species

Toothless

as Dim in A Sponge's Life (1996) (fan-made)

Starfire (Teen Titans)

as Best Non-Disney Princesses in Best & Worst of Cartoons

Amy Rose (SCU)

as Kimiko Glenn in Voice Actors & Actresses For Characters To Be Voiced

Tuke (Brother Bear)

as Seth Rogen in Voice Actors & Actresses For Characters To Be Voiced

Donkey Kong (The Super Mario Bros Movie)

as Seth Rogen in Voice Actors & Actresses For Characters To Be Voiced

Master Mantis

as Seth Rogen in Voice Actors & Actresses For Characters To Be Voiced

Sticks the Badger

as Nika Futterman in Voice Actors & Actresses For Characters To Be Voiced

Dr. Greed

as Tom Kenny in Voice Actors & Actresses For Characters To Be Voiced

SpongeBob SquarePants

as Tom Kenny in Voice Actors & Actresses For Characters To Be Voiced

Bert (Sesame Street)

as Rodger Bumpass in Voice Actors & Actresses For Characters To Be Voiced

Ord (Dragon Tales)

as Bill Fagerbakke in Voice Actors & Actresses For Characters To Be Voiced

Ernie (Sesame Street)

as Bill Fagerbakke in Voice Actors & Actresses For Characters To Be Voiced

Carmen Verde

as Grey DeLisle in Voice Actors & Actresses For Characters To Be Voiced

Alan Keane

as Tara Strong in Voice Actors & Actresses For Characters To Be Voiced

Cookie Monster

as Kevin Michael Richardson in Voice Actors & Actresses For Characters To Be Voiced

Twilight Sparkle

as Tara Strong in Voice Actors & Actresses For Characters To Be Voiced

Rarity

as Grey DeLisle in Voice Actors & Actresses For Characters To Be Voiced

Russi Taylor

as Teri in The Amazing World of Gumball (2001-2009)