What episode of Pokemon does dawn wear the blue dress?

Dawn wears a blue dress in several episodes of Pokemon, but it's difficult to give you a specific one without more context. Could you please provide more information about the dress you are referring to? For example:

* What anime season is it from? (Diamond & Pearl, Black & White, etc.)

* What is the occasion? (Contest, special event, casual outfit)

* Any other details about the dress? (Style, length, embellishments)

With more information, I can help you find the specific episode you are looking for!