The episodes with Dawn performing in contests, I want all the episode numbers, thx!
Here are all of the Sinnoh Ribbon Episodes:
Episode 495Floaroma Ribbon
Episode 547:Aqua Ribbon
Episode 563:Celestic Ribbon
Episode 582:Chocovine Ribbon
Episode 630:Daybreak Ribbon
Grand Festival Ranking Episode:Episode 646
Jublife Contest:Episode 480
Unofficial Contest: Episode 490
Hearthome Contest: Episode 517
Solaceon Contest:Episode 529
Sandalstraw Contest:Episode 591
Lilypad Contest: Episode 614
There are other, miscellaneous Contests from Dawn here- http://bulbapedia.bulbagarden.net/wiki/Dawn_(anime)#Sinnoh_Ribbons.
Hope this helps!