The United Coalition of Arco Iris

 is the eighteenth episode of the third season of Star Teens Unite!.

Summary
The Star Teens, Princess Amelie, and King Amadeus are trying to form a "united coalition" to prevent the outbreak of major conflicts between the other nearby kingdoms of Arco Iris. But when a great evil returns to threaten Arco Iris, it's up to the Star Teens and Princess Amelie, with the help of the other kingdoms, to protect Arco Iris.

Characters

 * Ella
 * Inidra
 * Sandra
 * Felicia
 * Lisa
 * Tanya
 * Sheila
 * Bella
 * Princess Amelie
 * King Amadeus
 * Trixie (Ella's mother)

Voice Cast

 * Aimee Carrero - Tanya
 * Colleen O'Shaughnessey - Princess Amelie, Trixie
 * Grey Griffin - Sandra
 * John Rhys Davies - King Amadeus
 * Kari Wahlgren - Ella
 * Kate Micucci - Inidra
 * Kimberly Brooks - Sheila
 * Susanne Blakeslee - Bella
 * Tara Strong - Felicia
 * Vyvan Pham - Lisa

Trivia

 * The "united coalition" concept is similar to the United Nations.
 * The sixth time that every Star Teen (even normal girls) are masked throughout, the first being Masked in Seattle, Vampira City, The Search for The White Knight, To The Rescue, and Restoring Orlando. Here, at the episode's start, Ella and the girls are perfoming their ritual.