The Little Sister

Candace (from Phineas and ferb) as Ariel

Tails (from sonic) as Flounder

Rabbit (from winnie the pooh) as Sebastian

Jeremy (from phineas and ferb) as Prince Eric

Tigger (from winnie the pooh) as Scuttle

Buzz Lightyear (from toy story) as King Triton

Keren (from spongebob) Ursula