Season 2 Episode 15 is a show focused on integrity and honesty of the Apple family, which included rainbow dash, twilight sparkale, pinkie pie, fluttershy, applejack, rarity, old grandma, apple bloom and big mac.
The apple family originally only the apple descendants were always having the trouble to produce enough apple cider. Then, the 2 brothers came into ponyville with the "Super Speedy Cider Squeezy 6000".
The apple family encountered the temptation to give up on integrity and win the competition. However, twilight sparkale and grandma persuaded rainbow dash not to do so.
In the end, they lost the competition, however, they remained in ponyville because the two brothers did not have integrity, in producing cider apple juice and was forced to leave ponyville.
Applejack sends a letter to Celestia, the SWAG way - I didn't learn anything! HAHA.
End of short summary.