Sonic Rainboom (event)

From Equestripedia, the Archives of Equestria!

The Sonic Rainboom was a major event during which a filly named Rainbow Dash performed a Sonic Rainboom in a race to defend Fluttershy's honor from a group of Cloudsdale bullies. The Sonic Rainboom caused six fillies across Equestria to discover their special talents and obtain their cutie marks:

These six ponies later became best friends and ended up living in Ponyville together. They later shared the story of the Sonic Rainboom to the Cutie Mark Crusaders, hoping to help them obtain their own cutie marks.[1]