Panel 1: Celestia used Protect - Luna use to-your-Face Kick - It is no effective. Panel 2: Celestia used Bite - It very effective - Luna used "AAAAHHHHH". Panel 3: Luna used Solar Beam - Celestia is flinched. Panel 4: Celestia used Block - Luna used Block. Panel 5: Luna used Distract - It is super duper effective (even the user fell for it). Panel 6: Little Twilight has run away. Panel 7: Luna and Celestia used Fly!!! (Lol, nameless baby!!!) Panel 8: Candace used "Shhhhh" - It is super duper wuper effective!!!
The manes do not have to flow to be a princess. Supposedly two theories come to mind with the flowing hair. 1. They do it by choice using magic to create the flowing effect. 2. They have an excessive amount of magical force built up in them which either is expelled through the hair or merely signified by the hair appearing as so.