Suggestions by @cartoonmultiverse

Raphael (TMNT 2007)

as Raph (07) in Aang

Donatello (Rise of the TMNT)

as Donnie (Rise) in Aang

Donatello (TMNT: Mutant Mayhem)

as Donnie (MM) in Aang

Leonardo (Rise of the TMNT)

as Leo (Rise) in Aang

Leonardo (TMNT 2003)

as Leo (03) in Aang

Leonardo (TMNT 2007)

as Leo (07) in Aang

Doctor Strange (Marvel Cinematic Universe)

as Doctor Strange in Aang

Invincible (Mark Grayson)

as Mark Grayson/Invincible in Aang

Vox (Hazbin Hotel)

as Vox in Aang

Mommy and Daddy (Caillou)

as Doris and Boris Anderson in Aang

Raphael (TMNT: Mutant Mayhem)

as Raph (MM) in Aang

Natsu Dragneel

as Natsu in Aang

Clementine (Caillou)

as Young Katara in Aang

Katara

as Katara in Aang

Nick Fury (Marvel Cinematic Universe)

as Nick Fury in Aang

Michelangelo (TMNT 2012)

as Mikey in Aang

Pom (Babar)

as Young Aang in Aang

Raphael (TMNT 2012)

as Raph in Aang

Leonardo (TMNT 2012)

as Leo in Aang

Spider-Man (The Spectacular Spider-Man)

as Peter Parker/Spiderman (Earth 16) in Aang