DucktheGWREngineFan9's Thomas/The Little Mermaid (Thomas as Sebastian only)

Cast

 * Emily as Ariel
 * James as Prince Eric
 * Konata (Lucky Star) as Melody
 * Percy as Flounder
 * Duck as Adult Flounder
 * Oliver as Scuttle
 * Trevor as Seahorse
 * Gordon as King Triton
 * Thomas as Sebastian (I think Thomas makes a better Sebastian)
 * Edward as Grim
 * Toad as Max
 * Caroline as Carolotta
 * Daisy as Ursula
 * Elizabeth as Vanessa
 * Arry and Bert as Flotsam and Jetsam
 * Spencer as Chef Louis (Both of them wear white)
 * Mavis as Arista
 * Lady as Attina
 * Madge as Adella
 * Flora as Andrina
 * Isobella as Alana
 * Belle as Aquata
 * Diesel 10 as The Shark (a.k.a. Glut the Shark)
 * Henry, Toby, Donald, Douglas, Stepney and Skarloey Engines as Animals
 * Diesel as The Hammerd Shark
 * Troublesome Trucks as The Eels
 * Elizabeth as Marina Del Rey
 * Smudger as Benjamin
 * George as Undertow
 * Bill and Ben as Tip and Dash
 * Max and Monty as Cloak and Dagger