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.

Major Events
The Star Teens attend the United Coalition

Characters

 * Ella
 * Kevin/The White Knight
 * Inidra
 * Sandra
 * Felicia
 * Lisa
 * Tanya
 * Sheila
 * Bella
 * Princess Amelie
 * King Amadeus

Voice Cast

 * Aimee Carrero - Tanya
 * Colleen O'Shaughnessey - Princess Amelie
 * Grey Griffin - Sandra
 * Josh Keaton - Kevin/The White Knight
 * Kari Wahlgren - Ella
 * Kate Micucci - Inidra
 * Keith Ferguson - King Amadeus
 * Kimberly Brooks - Sheila
 * Susanne Blakeslee - Bella
 * Tara Strong - Felicia
 * Vyvan Pham - Lisa

Trivia

 * The "united coalition" concept is similar to the United Nations.